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Edexcel International A Level Maths · P3 · Pure Mathematics 3

Integration of standard functions

28 free, high-quality past-paper-style questions on Integration of standard functions for Edexcel IAL Maths, each with a full mark scheme. For when you have finished the past papers, or want to practise one topic at a time.IAL Maths notes and flashcards →Not sure of your level? Diagnostic test →Multiple choice or structured questions, with the mark scheme as a separate PDF.28 new this month · 229 marks · Updated 26 October 2026 · Created by Evan Kotronis with AI assistance · How questions are checked

1IALM-P3-7-B-01 P3 · A2Easy5 marks

Throughout this question, x > 0.

(a)

Find ∫(6ex − 5/x + 3 cos x) dx.

(3)
(b)

Show that ∫1e (2 + 3/x) dx = 2e + 1.

(2)
Show mark scheme
AnswerMarkNotes
Part (a)
integrates at least two of the three terms correctlyM1
6ex − 5 ln xA1
6ex − 5 ln x + 3 sin x + c, all correct including + cA1
Part (b)
[2x + 3 ln x] with the limits 1 and e substitutedM1
(2e + 3 ln e) − (2 + 3 ln 1) = 2e + 3 − 2 = 2e + 1A1

Exam tip: ln e = 1 and ln 1 = 0. Write them out when you substitute limits in a show-that, so every step is visible.

2IALM-P3-7-B-02 P3 · A2Easy6 marks

Find each of the following integrals.

(a)

∫(4x + 1)6 dx

(2)
(b)

∫3/(2x − 1)2 dx, x > ½

(2)
(c)

∫cos(3x − π/4) dx

(2)
Show mark scheme
AnswerMarkNotes
Part (a)
k(4x + 1)7M1
(4x + 1)7/28 + cA1
Part (b)
writes as 3(2x − 1)−2 and obtains k(2x − 1)−1M1
−3/(2(2x − 1)) + cA1
Part (c)
k sin(3x − π/4)M1
⅓ sin(3x − π/4) + cA1

Common error: Forgetting to divide by the coefficient of x. Differentiate your answer: (4x + 1)7/7 gives 4(4x + 1)6, which is 4 times too big.

3IALM-P3-7-B-03 P3 · A2Easy6 marks

This question is about integrals of exponential functions.

(a)

Find the exact value of ∫0ln 3 e2x dx.

(3)
(b)

Expand (ex + e−x)2 and hence find ∫(ex + e−x)2 dx.

(3)
Show mark scheme
AnswerMarkNotes
Part (a)
[½e2x]M1
uses e2 ln 3 = 9: ½(9 − 1)M1
4A1
Part (b)
e2x + 2 + e−2xB1
integrates an exponential term with factor ½ or −½M1
½e2x + 2x − ½e−2x + cA1

Exam tip: ex × e−x = e0 = 1, so the middle term of the expansion is a constant, 2, which integrates to 2x.

4IALM-P3-7-B-04 P3 · A2Easy5 marks

In each integral the numerator is related to the derivative of the denominator.

(a)

Find ∫(2x + 3)/(x2 + 3x + 5) dx.

(2)
(b)

Show that ∫02 4x/(x2 + 1) dx = 2 ln 5.

(3)
Show mark scheme
AnswerMarkNotes
Part (a)
recognises the numerator as the derivative of the denominatorM1
ln(x2 + 3x + 5) + c (modulus optional: the quadratic is always positive)A1
Part (b)
k ln(x2 + 1)M1
2 ln(x2 + 1)A1
2 ln 5 − 2 ln 1 = 2 ln 5A1

Exam tip: The derivative of x2 + 1 is 2x, and 4x = 2 × 2x. Pull the 2 outside the integral before writing the logarithm.

5IALM-P3-7-FB-01 P3 · A2Easy7 marks

Figure 1 shows part of the curve C with equation y = 8/(2x + 1), x ≥ 0. C meets the y-axis at A(0, 8) and the line x = 4 at the point B. The shaded region R is bounded by C, the coordinate axes and the line x = 4. The chord AB is shown dashed.

xy123452468OA(0, 8)Bx = 4RC
(a)

Find ∫ 8/(2x + 1) dx.

(2)
(b)

Show that the area of R is 8 ln 3.

(2)
(c)

Find the exact area of the region between C and the chord AB.

(3)
Show mark scheme
AnswerMarkNotes
Part (a)
k ln(2x + 1)M1
4 ln(2x + 1) + cA1
Part (b)
[4 ln(2x + 1)]04 = 4 ln 9 − 4 ln 1M1
= 4 ln 9 = 8 ln 3A1
Part (c)
B is (4, 8/9); area under AB is the trapezium ½ × 4 × (8 + 8/9)M1
= 160/9A1
area between chord and curve = 160/9 − 8 ln 3A1

Common error: Writing 8 ln(2x + 1) and forgetting to divide by the coefficient of x. Differentiate the answer: d/dx[4 ln(2x + 1)] = 4 × 2/(2x + 1) = 8/(2x + 1), as required.

6IALM-P3-7-FB-02 P3 · A2Easy5 marks

Figure 1 shows the curve with equation y = 1 + 2 sin 2x, 0 ≤ x ≤ π. The curve crosses the x-axis at the points P and Q. The shaded region R is bounded by the curve and the coordinate axes, between the y-axis and P.

xyπ/6π/3π/22π/35π/6π−1123OPQRy = 1 + 2 sin 2x
(a)

Find the exact x-coordinate of P.

(2)
(b)

Find the exact area of R.

(3)
Show mark scheme
AnswerMarkNotes
Part (a)
sin 2x = −½, with 2x in the range 0 ≤ 2x ≤ 2πM1
2x = 7π/6, so x = 7π/12 (Q is at 11π/12)A1
Part (b)
integrates 2 sin 2x to k cos 2xM1
x − cos 2xA1
(7π/12 − cos(7π/6)) − (0 − cos 0) = 7π/12 + √3/2 + 1A1

Exam tip: Read the order of the roots from the figure. P is the first crossing, so take the smallest solution of sin 2x = −½ in range; 2x = 7π/6 comes before 2x = 11π/6.

7IALM-P3-7-FB-03 P3 · A2Easy7 marks

Figure 1 shows the curve C with equation y = ae−kx, where a and k are positive constants. C passes through the points A(0, 12) and B(ln 4, 6). The region R is bounded by C, the coordinate axes and the line x = ln 16. The vertical line through B divides R into the two regions R1 and R2.

xy12324681012OA(0, 12)B(ln 4, 6)x = ln 16R₁R₂C
(a)

Find the value of a and the value of k.

(2)
(b)

Find ∫ 12e−x/2 dx.

(2)
(c)

Show that the areas of R1 and R2 are in the ratio 2 : 1.

(3)
Show mark scheme
AnswerMarkNotes
Part (a)
a = 12 from AB1
12e−k ln 4 = 6, so 4−k = ½ and k = ½B1
Part (b)
ke−x/2M1
−24e−x/2 + cA1
Part (c)
R1 = [−24e−x/2]0ln 4 = −24 × ½ + 24M1
= 12A1
R2 = −24 × ¼ + 24 × ½ = 6, using e−½ ln 16 = ¼; 12 : 6 = 2 : 1A1

Exam tip: e−½ ln 4 = eln(4−½) = ½. Turning the exponential of a logarithm into a number before you subtract keeps the arithmetic short.

8IALM-P3-7-FB-04 P3 · A2Easy5 marks

Figure 1 shows part of the curve with equation y = 6x/(x2 + 3), x ≥ 0. The shaded region R is bounded by the curve, the x-axis and the lines x = 1 and x = 3.

xy123450.511.52Ox = 1x = 3Ry = 6x/(x2 + 3)
(a)

Find ∫ 6x/(x2 + 3) dx.

(2)
(b)

Find the exact area of R, giving your answer in the form p ln q, where p and q are integers.

(3)
Show mark scheme
AnswerMarkNotes
Part (a)
recognises the numerator as a multiple of the derivative of x2 + 3: k ln(x2 + 3)M1
3 ln(x2 + 3) + cA1
Part (b)
[3 ln(x2 + 3)]13M1
3 ln 12 − 3 ln 4A1
3 ln 3A1

Common error: Writing 6 ln(x2 + 3). The derivative of x2 + 3 is 2x, and 6x is three times that, so the logarithm is multiplied by 3, not 6.

9IALM-P3-7-B-05 P3 · A2Medium7 marks

Squared trigonometric functions can be integrated after rewriting them with an identity.

(a)

Using the identity cos 2A ≡ 1 − 2 sin²A, show that sin²3x ≡ ½(1 − cos 6x).

(1)
(b)

Hence find ∫sin²3x dx.

(3)
(c)

Find the exact value of ∫0π/4 tan²x dx.

(3)
Show mark scheme
AnswerMarkNotes
Part (a)
with A = 3x: cos 6x = 1 − 2 sin²3x, rearranged to sin²3x = ½(1 − cos 6x)B1
Part (b)
½xB1
k sin 6xM1
½x − (1/12) sin 6x + cA1
Part (c)
uses tan²x = sec²x − 1M1
[tan x − x]A1
1 − π/4A1

Common error: Writing ∫sin²3x dx = sin³3x/9. The square is of a function, not of x; use the identity to remove it first.

10IALM-P3-7-B-06 P3 · A2Medium7 marks

Each integral below is a power of a function multiplied by a multiple of its derivative.

(a)

By differentiating (3x2 + 1)5, or otherwise, find ∫x(3x2 + 1)4 dx.

(3)
(b)

Show that ∫0π/3 sin x/cos²x dx = 1.

(4)
Show mark scheme
AnswerMarkNotes
Part (a)
k(3x2 + 1)5M1
d/dx(3x2 + 1)5 = 30x(3x2 + 1)4, or equivalent adjustmentM1
(3x2 + 1)5/30 + cA1
Part (b)
writes the integrand as sin x(cos x)−2, or as sec x tan xM1
integrates to (cos x)−1 = sec xA1
substitutes the limits: sec(π/3) − sec 0M1
2 − 1 = 1A1

Exam tip: sin x/cos²x is also sec x tan x, the derivative of sec x (in the formulae booklet). Either route gives sec x.

11IALM-P3-7-B-07 P3 · A2Medium8 marks

Gas leaks from a damaged container. The rate of leakage is modelled by R = 12e−0.4t, where R is measured in kg per hour and t is the time in hours after the leak begins. The container held 35 kg of gas when the leak began.

(a)

Show that the mass of gas that leaks in the first 5 hours is 30(1 − e−2) kg, and find this mass to 3 significant figures.

(4)
(b)

Explain why, according to the model, the container never becomes empty.

(1)
(c)

Find the time after the leak begins at which 15 kg of gas has leaked, giving your answer in hours to 3 significant figures.

(3)
Show mark scheme
AnswerMarkNotes
Part (a)
integrates to ke−0.4tM1
−30e−0.4tA1
limits 0 and 5: −30e−2 + 30 = 30(1 − e−2)M1
25.9 kgA1
Part (b)
mass leaked by time T is 30(1 − e−0.4T), which is always less than 30, and 30 < 35B1
Part (c)
30(1 − e−0.4T) = 15M1
e−0.4T = ½, so T = (ln 2)/0.4M1
1.73 hoursA1

Model sketch

5104812t (hours)R (kg per hour)R = 12e^(−0.4t)30(1 − e⁻²)
Figure: the mass leaked in the first 5 hours is the shaded area

Exam tip: The integral of a rate between two times is the total change in that time. Here the period starts when the leak begins, so the lower limit is t = 0.

12IALM-P3-7-B-08 P3 · A2Medium7 marks

The function f is defined by f(x) = 6/(1 − 2x), x ∈ ℝ, x ≠ ½.

(a)

Find ∫f(x) dx.

(2)
(b)

Find the exact value of ∫13 f(x) dx, giving your answer in the form a ln b, where a and b are integers.

(3)
(c)

Explain why the answer to part (b) is negative, and why the same method cannot be used to find ∫01 f(x) dx.

(2)
Show mark scheme
AnswerMarkNotes
Part (a)
k ln|1 − 2x|M1
−3 ln|1 − 2x| + cA1
Part (b)
substitutes the limits into their −3 ln|1 − 2x|M1
uses the moduli correctly: −3(ln|−5| − ln|−1|)M1
−3 ln 5A1
Part (c)
f(x) < 0 for x > ½, so the region between the curve and the x-axis lies below the axisB1
f is not defined at x = ½, which lies between 0 and 1 (the curve has a vertical asymptote there)B1

Model sketch

13Oxyy = f(x)x = ½
Figure: the region for 1 ≤ x ≤ 3 lies below the x-axis; x = ½ is an asymptote

Common error: Writing ln(1 − 2x) without the modulus and then trying to take ln of −5. On 1 ≤ x ≤ 3, 1 − 2x is negative, so the modulus is essential.

13IALM-P3-7-B-09 P3 · A2Medium8 marks

Each of the following integrals can be found by recognising the derivative of the denominator.

(a)

Find ∫sin 2x/(1 + cos²x) dx.

(3)
(b)

Hence show that ∫0π/2 sin 2x/(1 + cos²x) dx = ln 2.

(2)
(c)

Find the exact value of ∫0π/6 (cos x − sin x)/(cos x + sin x) dx, giving your answer in the form ln((√p + 1)/q), where p and q are integers.

(3)
Show mark scheme
AnswerMarkNotes
Part (a)
d/dx(1 + cos²x) = −2 sin x cos x = −sin 2xM1
k ln(1 + cos²x)M1
−ln(1 + cos²x) + cA1
Part (b)
−ln(1 + 0) + ln(1 + 1)M1
= ln 2A1
Part (c)
recognises the numerator as the derivative of cos x + sin xM1
[ln(cos x + sin x)] evaluated: ln(√3/2 + ½) − ln 1M1
ln((√3 + 1)/2)A1

Exam tip: sin 2x = 2 sin x cos x appears whenever cos²x or sin²x is differentiated. Spotting it turns an awkward fraction into f′/f.

14IALM-P3-7-B-10 P3 · A2Medium8 marks

The curve C has equation y = 5 − ex − 4e−x. The finite region R is bounded by C and the x-axis.

OxyCR
Figure: the region R between C and the x-axis; not to scale
(a)

Show that the x-coordinates of the points where C meets the x-axis satisfy (ex − 1)(ex − 4) = 0, and hence find these x-coordinates exactly.

(3)
(b)

Show that the area of R is 10 ln 2 − 6.

(5)
Show mark scheme
AnswerMarkNotes
Part (a)
multiplies 5 − ex − 4e−x = 0 by ex: 5ex − e2x − 4 = 0M1
e2x − 5ex + 4 = 0, so (ex − 1)(ex − 4) = 0A1
x = 0 and x = ln 4A1
Part (b)
integrates, obtaining ke−x from 4e−xM1
[5x − ex + 4e−x]A1
uses their limits 0 and ln 4M1
uses e−ln 4 = ¼: (5 ln 4 − 4 + 1) − (0 − 1 + 4)M1
= 10 ln 2 − 6A1

Exam tip: An equation in ex and e−x becomes a quadratic in ex once you multiply through by ex.

15IALM-P3-7-FB-05 P3 · A2Medium8 marks

Figure 1 shows the curve C with equation y = 4 cos²x, 0 ≤ x ≤ π, and the line L with equation y = 1. L meets C at the points P and Q. The shaded region R is bounded by C, L and the y-axis.

xyπ/6π/3π/22π/35π/6π1234OPQRLy = 4 cos2 x
(a)

Show that 4 cos²x ≡ 2 + 2 cos 2x.

(1)
(b)

Find the exact x-coordinates of P and Q.

(3)
(c)

Find the exact area of R.

(4)
Show mark scheme
AnswerMarkNotes
Part (a)
uses cos 2x ≡ 2 cos²x − 1, so 4 cos²x ≡ 2(1 + cos 2x) ≡ 2 + 2 cos 2xB1
Part (b)
4 cos²x = 1, so cos x = ±½M1
P: x = π/3A1
Q: x = 2π/3A1
Part (c)
area = ∫0π/3 (2 + 2 cos 2x − 1) dxM1
x + sin 2xA1
substitutes the limits 0 and their π/3M1
π/3 + √3/2A1

Common error: Forgetting the negative root. cos²x = ¼ gives cos x = ½ or cos x = −½, and the second one gives Q. Figure 1 shows two crossings, so you need both.

16IALM-P3-7-FB-06 P3 · A2Medium7 marks

A cyclist starts from rest. The speed of the cyclist, v m s−1, t seconds after starting is modelled by v = V(1 − e−t/2), t ≥ 0, where V is a constant. Figure 1 shows the graph of v against t; the dashed line is the asymptote that the graph approaches as t increases.

t / sv / m s−12468102468Ov = 8first 6 s
(a)

Use Figure 1 to state the value of V.

(1)
(b)

Find the distance travelled by the cyclist in the first 6 seconds, giving your answer in the form p + qe−3 and then to 3 significant figures.

(4)
(c)

Find the time taken for the cyclist to reach a speed of 6 m s−1, giving your answer in seconds to 3 significant figures.

(2)
Show mark scheme
AnswerMarkNotes
Part (a)
as t → ∞, e−t/2 → 0, so v → V; from the asymptote V = 8B1
Part (b)
distance = ∫06 8(1 − e−t/2) dtM1
8t + 16e−t/2A1
(48 + 16e−3) − (0 + 16)M1
32 + 16e−3 = 32.8 mA1
Part (c)
8(1 − e−t/2) = 6, so e−t/2 = ¼M1
t = 2 ln 4 = 2.77 sA1

Exam tip: Distance is the area under a speed–time graph. Here the speed is given by a formula, so the area is found by integrating with respect to time between the two times.

17IALM-P3-7-FB-07 P3 · A2Medium9 marks

Figure 1 shows the curve C with equation y = x√(16 − x2), 0 ≤ x ≤ 4. C has a maximum point M(2√2, 8). The region R is bounded by C and the x-axis. The region S, shaded darker, is bounded by C and the straight line OM, where O is the origin.

xy12342468OM(2√2, 8)SR
(a)

By considering the derivative of (16 − x2)3/2, find ∫ x(16 − x2)½ dx.

(3)
(b)

Show that the area of R is 64/3.

(2)
(c)

Find the exact area of S, giving your answer in the form (p + q√2)/3, where p and q are integers.

(4)
Show mark scheme
AnswerMarkNotes
Part (a)
k(16 − x2)3/2M1
d/dx(16 − x2)3/2 = −3x(16 − x2)½, so k = −⅓M1
−⅓(16 − x2)3/2 + cA1
Part (b)
[−⅓(16 − x2)3/2]04 = 0 − (−⅓ × 64)M1
= 64/3A1
Part (c)
area under C from 0 to 2√2: 64/3 − ⅓ × 83/2M1
= 64/3 − 16√2/3A1
subtracts the triangle under OM: ½ × 2√2 × 8 = 8√2M1
(64 − 40√2)/3A1

Exam tip: The x outside the bracket is (apart from a constant) the derivative of the expression inside. Guess k(16 − x2)3/2, differentiate, and choose k to match.

18IALM-P3-7-FB-08 P3 · A2Medium9 marks

Figure 1 shows part of the curve C with equation y = (x − 4)/(x + 2), x > −2. C crosses the y-axis at (0, −2) and the x-axis at (4, 0). The region R1 lies below the x-axis and is bounded by C and the coordinate axes. The region R2 lies above the x-axis and is bounded by C, the x-axis and the line x = 10.

xy246810−2−1O(0, −2)x = 10y = 1R₁R₂C
(a)

Show that y = 1 − 6/(x + 2).

(2)
(b)

Find the exact area of R1.

(4)
(c)

Find the exact value of ∫010 y dx, and explain how it is related to the areas of R1 and R2.

(3)
Show mark scheme
AnswerMarkNotes
Part (a)
writes x − 4 as (x + 2) − 6, or uses divisionM1
(x + 2)/(x + 2) − 6/(x + 2) = 1 − 6/(x + 2)A1
Part (b)
integrates to x + k ln(x + 2)M1
x − 6 ln(x + 2)A1
(4 − 6 ln 6) − (0 − 6 ln 2) = 4 − 6 ln 3M1
area is the positive value: 6 ln 3 − 4A1
Part (c)
(10 − 6 ln 12) − (0 − 6 ln 2)M1
10 − 6 ln 6A1
the integral counts R1 as negative, so it equals area of R2 − area of R1B1

Common error: Quoting 4 − 6 ln 3 as an area. Below the x-axis the integral is negative (about −2.59); the area is its size, 6 ln 3 − 4.

19IALM-P3-7-FB-09 P3 · A2Medium9 marks

Figure 1 shows the curves with equations y = 2 sin x and y = tan x, 0 ≤ x < π/2. The curves meet at the origin O and at the point P. The shaded region R is bounded by the two curves between O and P.

xyπ/6π/3π/2123OPRy = 2 sin xy = tan x
(a)

By writing tan x as sin x/cos x, show that ∫ tan x dx = ln|sec x| + c.

(2)
(b)

Find the coordinates of P.

(3)
(c)

Find the exact area of R.

(4)
Show mark scheme
AnswerMarkNotes
Part (a)
sin x/cos x = −(−sin x)/cos x, the derivative of cos x over cos x, so the integral is −ln|cos x|M1
−ln|cos x| = ln|1/cos x| = ln|sec x| + cA1
Part (b)
2 sin x = sin x/cos x, so sin x(2 cos x − 1) = 0M1
cos x = ½, so x = π/3A1
P(π/3, √3)A1
Part (c)
area = ∫0π/3 (2 sin x − tan x) dxM1
−2 cos x − ln|sec x|A1
substitutes: (−1 − ln 2) − (−2 − ln 1)M1
1 − ln 2A1

Common error: Dividing both sides of 2 sin x = tan x by sin x loses the solution sin x = 0, which is O. Factorise instead, so that both meeting points appear.

20IALM-P3-7-FB-10 P3 · A2Medium9 marks

Figure 1 shows part of the curve C with equation y = tan²x, 0 ≤ x < π/2, and the line y = 3. The line meets C at A, where x = π/3. The point B on C has x-coordinate π/4. The region R is bounded by C, the line y = 3 and the y-axis. The region S is bounded by C, the x-axis and the vertical lines through B and A.

xyπ/6π/4π/3π/21234OABRSy = 3y = tan2 x
(a)

Show that ∫ tan²x dx = tan x − x + c.

(2)
(b)

Find the exact area of R.

(4)
(c)

Find the exact area of S.

(3)
Show mark scheme
AnswerMarkNotes
Part (a)
uses tan²x = sec²x − 1M1
integrates sec²x to tan x: tan x − x + cA1
Part (b)
area = ∫0π/3 (3 − tan²x) dxM1
= ∫(4 − sec²x) dx = [4x − tan x]A1
substitutes 0 and π/3M1
4π/3 − √3A1
Part (c)
[tan x − x]π/4π/3M1
(√3 − π/3) − (1 − π/4)M1
√3 − 1 − π/12A1

Exam tip: R lies between the line (above) and the curve (below), so integrate (3 − tan²x). Rewriting tan²x as sec²x − 1 first turns the integrand into 4 − sec²x.

21IALM-P3-7-B-11 P3 · A2Hard10 marks

The curves y = 2 sin²x and y = sin x are drawn for 0 ≤ x ≤ π. For π/6 ≤ x ≤ 5π/6 the curve y = 2 sin²x lies on or above the curve y = sin x, and the finite region R lies between the two curves for π/6 ≤ x ≤ 5π/6.

(a)

Find the x-coordinates of all the points where the two curves meet for 0 ≤ x ≤ π.

(3)
(b)

Show that 2 sin²x ≡ 1 − cos 2x.

(1)
(c)

Show that the area of R is 2π/3 − √3/2.

(6)
Show mark scheme
AnswerMarkNotes
Part (a)
2 sin²x − sin x = 0, so sin x(2 sin x − 1) = 0M1
sin x = 0: x = 0, πA1
sin x = ½: x = π/6, 5π/6A1
Part (b)
from cos 2x ≡ 1 − 2 sin²x, rearrangedB1
Part (c)
area = ∫π/65π/6 (1 − cos 2x − sin x) dxM1
x − ½ sin 2xA1
+ cos xA1
substitutes both limits into their integralM1
uses exact values sin(5π/3) = −√3/2, sin(π/3) = √3/2, cos(5π/6) = −√3/2, cos(π/6) = √3/2M1
(5π/6 + √3/4 − √3/2) − (π/6 − √3/4 + √3/2) = 2π/3 − √3/2A1

Model sketch

π/6π/25π/6πxyy = 2 sin²xy = sin xR
Figure: the curves y = 2 sin²x and y = sin x, with R shaded

Exam tip: When solving 2 sin²x = sin x, never divide by sin x: you would lose the solutions x = 0 and x = π. Factorise instead.

22IALM-P3-7-B-12 P3 · A2Hard12 marks

The curve C has equation y = (x2 + 2x + 5)/(x + 1), x > −1. The line l has equation y = x + 3.

13OxyClx = 3
Figure: C, l and the line x = 3; the finite region bounded by C, l and the y-axis is shaded
(a)

Show that y = x + 1 + 4/(x + 1).

(2)
(b)

Find the exact area of the region bounded by C, the coordinate axes and the line x = 3, giving your answer in the form p + q ln 2, where p and q are rational.

(4)
(c)

Show that l meets C at exactly one point, where x = 1.

(2)
(d)

Find the exact area of the finite region bounded by C, l and the y-axis.

(4)
Show mark scheme
AnswerMarkNotes
Part (a)
writes x2 + 2x + 5 = (x + 1)2 + 4, or uses algebraic divisionM1
divides by x + 1 to obtain x + 1 + 4/(x + 1)A1
Part (b)
integrates, obtaining a k ln(x + 1) termM1
½x2 + x + 4 ln(x + 1)A1
substitutes 3 and 0: (9/2 + 3 + 4 ln 4) − 0M1
15/2 + 8 ln 2A1
Part (c)
x + 1 + 4/(x + 1) = x + 3, so 4/(x + 1) = 2M1
x + 1 = 2, so x = 1, the only solutionA1
Part (d)
area = ∫01 (4/(x + 1) − 2) dx, using curve minus lineM1
[4 ln(x + 1) − 2x]A1
substitutes 1 and 0M1
4 ln 2 − 2A1

Exam tip: Rewriting an improper fraction as a polynomial plus a proper fraction is what makes it integrable here: the proper fraction gives the logarithm.

23IALM-P3-7-B-13 P3 · A2Hard11 marks

The function f is defined by f(x) = e2x/(e2x + 3), x ∈ ℝ. The region R is bounded by the curve y = f(x), the coordinate axes and the line x = ln 3.

ln 3Oxyy = f(x)R
Figure: the region R
(a)

Find ∫f(x) dx.

(2)
(b)

Find ∫e2x(e2x + 3)3 dx.

(3)
(c)

Show that the area of R is ½ ln 3.

(3)
(d)

The area of the region bounded by the curve, the coordinate axes and the line x = a, where a > 0, is ln 2. Find the exact value of a.

(3)
Show mark scheme
AnswerMarkNotes
Part (a)
k ln(e2x + 3)M1
½ ln(e2x + 3) + cA1
Part (b)
k(e2x + 3)4M1
d/dx(e2x + 3)4 = 8e2x(e2x + 3)3, or equivalent adjustmentM1
⅛(e2x + 3)4 + cA1
Part (c)
½[ln(e2x + 3)] with limits 0 and ln 3M1
uses e2 ln 3 = 9: ½ ln 12 − ½ ln 4M1
= ½ ln 3A1
Part (d)
½ ln((e2a + 3)/4) = ln 2M1
(e2a + 3)/4 = 4, so e2a = 13M1
a = ½ ln 13A1

Exam tip: Both integrals use the same inside function, e2x + 3, whose derivative is 2e2x. Write that derivative down first; it tells you the constant to divide by.

24IALM-P3-7-B-14 P3 · A2Hard10 marks

Water flows into a reservoir. The rate of flow, R m3 per hour, t hours after midnight, is modelled by R = 3 + 2 sin²(πt/12), 0 ≤ t ≤ 24.

(a)

Show that R = 4 − cos(πt/6).

(2)
(b)

Find the total volume of water that flows into the reservoir in the 24 hours.

(3)
(c)

Find the volume of water that flows into the reservoir between midnight and 3 a.m., giving your answer to 3 significant figures.

(3)
(d)

State the greatest rate of flow according to the model, and the times at which it occurs.

(2)
Show mark scheme
AnswerMarkNotes
Part (a)
uses 2 sin²A = 1 − cos 2A with A = πt/12M1
3 + 1 − cos(πt/6) = 4 − cos(πt/6)A1
Part (b)
∫024 (4 − cos(πt/6)) dtM1
[4t − (6/π) sin(πt/6)]A1
96 m3A1
Part (c)
substitutes the limits 0 and 3 into their integralM1
12 − 6/πA1
10.1 m3A1
Part (d)
greatest rate 5 m3 per hour, when cos(πt/6) = −1B1
t = 6 and t = 18, i.e. at 06:00 and at 18:00B1

Model sketch

3612182412345t (hours)R (m³ per hour)R(6, 5)(18, 5)
Figure: rate of flow; the shaded area is the volume from midnight to 3 a.m.

Exam tip: In a model with π in the argument, the angle is in radians. Integrating cos(πt/6) divides by π/6, which multiplies by 6/π.

25IALM-P3-7-FB-11 P3 · A2Hard11 marks

The function f is defined for x > −½. Figure 1 shows the graph of y = f′(x), where f′(x) = 6/(2x + 1) − 2. The graph meets the y-axis at (0, 4) and the x-axis at P. The curve y = f(x) passes through the point (0, 3).

xy123424O(0, 4)Py = f′(x)y = −2x = −½
(a)

Find the x-coordinate of P.

(2)
(b)

Find f(x).

(4)
(c)

Using Figure 1, explain why the curve y = f(x) has a maximum point where x is the x-coordinate of P, and find the exact y-coordinate of this maximum point.

(3)
(d)

Show that the area of the shaded region in Figure 1 is 3 ln 3 − 2.

(2)
Show mark scheme
AnswerMarkNotes
Part (a)
6/(2x + 1) = 2, so 2x + 1 = 3M1
x = 1A1
Part (b)
integrates 6/(2x + 1) to k ln(2x + 1)M1
3 ln(2x + 1) − 2x + cA1
uses (0, 3): 3 ln 1 − 0 + c = 3M1
f(x) = 3 ln(2x + 1) − 2x + 3A1
Part (c)
f′(x) is positive to the left of P and negative to the right, so f changes from increasing to decreasingB1
substitutes x = 1 into their f(x): 3 ln 3 − 2 + 3M1
3 ln 3 + 1A1
Part (d)
area = ∫01 f′(x) dx = [f(x)]01M1
(3 ln 3 + 1) − 3 = 3 ln 3 − 2A1

Exam tip: The area under a graph of f′(x) between two values of x is the change in f between them. Once you have f(x), you do not need to integrate again.

26IALM-P3-7-FB-12 P3 · A2Hard11 marks

Figure 1 shows the front of an arched gateway. The arch is modelled by the curve with equation y = 4 sin(πx/6), 0 ≤ x ≤ 6, where x metres is the horizontal distance from O and y metres is the height above the ground. A horizontal bar PQ is fixed across the arch at a height of 2 m, with P and Q on the arch. The region between the bar and the arch is a glass fanlight.

x / my / m1234561234OPQfanlight
(a)

State the width of the gateway at ground level and its greatest height.

(2)
(b)

Find the exact area of the whole opening under the arch, that is, the region between the arch and the ground, including the fanlight.

(3)
(c)

Find the x-coordinates of P and Q.

(2)
(d)

Show that the area of the fanlight is (24√3/π − 8) m2, and find this area to 3 significant figures.

(4)
Show mark scheme
AnswerMarkNotes
Part (a)
sin(πx/6) = 0 at x = 0 and x = 6: width 6 mB1
greatest value of sin is 1, at x = 3: height 4 mB1
Part (b)
integrates to k cos(πx/6)M1
[−(24/π) cos(πx/6)]06A1
24/π + 24/π = 48/π m2A1
Part (c)
4 sin(πx/6) = 2, so sin(πx/6) = ½M1
πx/6 = π/6 or 5π/6: x = 1 and x = 5A1
Part (d)
area = ∫15 (4 sin(πx/6) − 2) dxM1
[−(24/π) cos(πx/6) − 2x]15A1
uses cos(5π/6) = −√3/2 and cos(π/6) = √3/2: (12√3/π − 10) − (−12√3/π − 2) = 24√3/π − 8A1
5.23 m2A1

Exam tip: Integrating sin(πx/6) divides by π/6, which is the same as multiplying by 6/π. With the factor 4 this gives −(24/π) cos(πx/6); differentiate it to check.

27IALM-P3-7-FB-13 P3 · A2Hard11 marks

Figure 1 shows part of the curve C with equation y = (ln x)/x, x > 0. C crosses the x-axis at the point A and has a maximum point at M. The shaded region R is bounded by C, the x-axis and the line x = e2.

xy12345678−0.20.20.4OAMx = e2Ry = (ln x)/x
(a)

Show that M has coordinates (e, 1/e).

(4)
(b)

By considering the derivative of (ln x)2, find ∫ (ln x)/x dx.

(2)
(c)

Show that the area of R is 2.

(2)
(d)

The region bounded by C, the x-axis and the lines x = e2 and x = k, where k > e2, has the same area as R. Find the exact value of k.

(3)
Show mark scheme
AnswerMarkNotes
Part (a)
uses the quotient ruleM1
dy/dx = (1 − ln x)/x2A1
sets 1 − ln x = 0, so x = eM1
y = (ln e)/e = 1/eA1
Part (b)
k(ln x)2, since d/dx(ln x)2 = 2(ln x)/xM1
½(ln x)2 + cA1
Part (c)
limits 1 (at A) and e2: ½(ln e2)2 − ½(ln 1)2M1
= ½ × 4 − 0 = 2A1
Part (d)
½(ln k)2 − 2 = 2M1
(ln k)2 = 8, ln k = 2√2 (taking the positive root as k > 1)M1
k = e2√2A1

Common error: Writing ∫ (ln x)/x dx = ln(ln x). That would be the integral of 1/(x ln x); here ln x is multiplied by its own derivative 1/x, so the answer is ½(ln x)2.

28IALM-P3-7-FB-14 P3 · A2Hard11 marks

Figure 1 shows the curves C1 and C2 with equations y = 4x/(x2 + 1)2 and y = x/(x2 + 1) respectively, for x ≥ 0. The curves meet at the origin and at the point P. The shaded region R is bounded by C1 and C2 between the origin and P.

xy12340.250.50.7511.25OPRC₁C₂
(a)

Find the exact x-coordinates of the points where C1 and C2 meet.

(3)
(b)

Find ∫ x/(x2 + 1) dx.

(2)
(c)

Find ∫ 4x/(x2 + 1)2 dx.

(2)
(d)

Show that the area of R is 3/2 − ln 2.

(4)
Show mark scheme
AnswerMarkNotes
Part (a)
4x/(x2 + 1)2 = x/(x2 + 1), so x[4 − (x2 + 1)] = 0M1
x = 0A1
x2 = 3, so x = √3 at P (x ≥ 0)A1
Part (b)
k ln(x2 + 1)M1
½ ln(x2 + 1) + cA1
Part (c)
k(x2 + 1)−1M1
−2/(x2 + 1) + cA1
Part (d)
area = ∫0√3 (C1 − C2) dx, with C1 aboveM1
[−2/(x2 + 1) − ½ ln(x2 + 1)]M1
(−½ − ½ ln 4) − (−2 − 0)M1
= 3/2 − ln 2A1

Exam tip: Both integrands contain the derivative 2x of x2 + 1. A first power underneath gives a logarithm; a square underneath gives a power, (x2 + 1)−1.