Mathematics 9709/11 May/June 2019: question paper and mark scheme
Cambridge AS & A Level Mathematics (9709), Paper 1, May/June 2019. Read both free below, or download them. Done the paper? Get it marked by AI against this mark scheme.
The term independent of x in the expansion of 2x + , where k is a constant, is 540. x
(i) Find the value of k. [3]
(ii) For this value of k, find the coefficient of x2 in the expansion. [2]
Mark scheme
1(i) k
3 B2,1,0 Term must be isolated
Ind term = ( 2 x ) × × 6C3
3
x
= 540 → k = 1½ B1
3
1(ii) k
2 B1 All correct – even if k incorrect.
Term, in x² is ( 2 x ) × × 6C2
4
x
15 × 16 × k² = 540 (or 540 x 2 ) B1 FT For 240k² or 240 k 2 x 2
2
The line 4y = x + c, where c is a constant, is a tangent to the curve y2 = x + 3 at the point P on the curve.
(i) Find the value of c. [3]
(ii) Find the coordinates of P. [2]
Mark scheme
2(i) Eliminates x or y → y ² − 4 y + c − 3 = 0 M1 Eliminates x or y completely to a quadratic
or x² + ( 2c − 16) x + c² − 48 = 0
Uses b ² = 4 ac → 4c – 28 = 0 M1 Uses discriminant = 0. (c the only variable)
Any valid method (may be seen in part (i))
c=7 A1
Alternative method for question 2(i)
dy 1 1 M1
= =
dx 2 ( x + 3) 4
Solving M1
c=7 A1
3
2(ii) Uses c = 7, y² − 4y + 4 = 0 M1 Ignore (1,–2), c=-9
(1, 2) A1
2
y
C h, 3h D
B
0, 2
x
O A 4, 0
The diagram shows a trapezium ABCD in which the coordinates of A, B and C are 4, 0, 0, 2 and h, 3h respectively. The lines BC and AD are parallel, angle ABC = 90Å and CD is parallel to the x-axis.
(i) Find, by calculation, the value of h. [3]
(ii) Hence find the coordinates of D. [3]
Mark scheme
4(i) Gradient of AB = −½ → Gradient of BC = 2 M1 Use of m1.m2 = −1 for correct lines
3h − 2 M1 Uses normal line equation or gradients for h.
Forms equation in h =2
h
h=2 A1
Alternative method for question 4(i)
Vectors AB.BC=0 M1 Use of vectors AB and BC
Solving M1
h=2 A1
Alternative method for question 4(i)
Use of Pythagoras to find 3 lengths M1
Solving M1
h=2 A1
3
4(ii) y coordinate of D is 6, (3 × ‘their’ h) B1 FT
6−0
= 2 → x = 7 → D (7, 6)
x−4
Vectors: AD.AB=0 M1 A1 Must use y = 6
Realises the y values of C and D are equal.
Uses gradient or line equation to find x.
3
The function f is defined by f x = −2x2 + 12x − 3 for x ∈ >.
(i) Express −2x2 + 12x − 3 in the form −2 x + a2 + b, where a and b are constants. [2]
(ii) State the greatest value of f x. [1]
The function g is defined by g x = 2x + 5 for x ∈ >.
(iii) Find the values of x for which gf x + 1 = 0. [3]
@ A2
1 1 − sin x
Mark scheme
5(i) −2 ( x − 3) + 15 (a = − 3, b = 15) B1 B1 Or seen as a = − 3, b = 15 B1 for each value
2
2
5(ii) (f(x) ⩽) 15 B1 FT for (⩽) their “b” Don’t accept (3,15) alone
1
5(iii) gf(x) = 2( −2 x ² + 12 x − 3 ) + 5 = −4x² + 24x – 6 + 5 B1
gf(x) + 1 = 0 → −4x² + 24x = 0 M1
x = 0 or 6 A1 Forms and attempts to solve a quadratic
Both answers given.
3
(i) Prove the identity − tan x . [4]
cos x 1 + sin x
@
A2
1
(ii) Hence solve the equation − tan 2x = 13 for 0 ≤ x ≤ 0. [3]
cos 2x
Mark scheme
6(i) 1 s
LHS = − =
(1 − s )(1 − s ) (1 − s )(1 − s )
2 B1 Expresses tan in terms of sin and cos
=
c c c² 1 − s2
B1 correctly 1– s2 as the denominator
(1 − s )(1 − s ) M1 Factors and correct cancelling www
=
(1 − s )(1 + s )
1 − sinx A1
AG
1 + sinx
4
6(ii) 1 − sin2 x 1 M1 Realises use of 2x and makes sin2x the subject
Uses part (i) to obtain = → sin 2x = ½
1 + sin2 x 3
π A1 Allow decimal (0.262)
x=
12
5π A1 FT for ½π – 1st answer.
(or) x = Allow decimal (1.31)
12
π 5π
and only, and no others in range.
12 12
π 5π
SC sinx=½ → B1
6 6
3
JJJJG
G
F
D
E
M
C
B k j
O i A
The diagram shows a three-dimensional shape in which the base OABC and the upper surface DEFG are identical horizontal squares. The parallelograms OAED and CBFG both lie in vertical planes.
The point M is the mid-point of AF.
Unit vectors i and j are parallel to OA and OC respectively and the unit vector k is vertically upwards.
−−→ −−→
The position vectors of A and D are given by OA = 8i and OD = 3i + 10k.
−−→ −−−→
(i) Express each of the vectors AM and GM in terms of i, j and k. [3]
(ii) Use a scalar product to find angle GMA correct to the nearest degree. [4]
Mark scheme
7(i) AM = 1.5i + 4j + 5k B3,2,1 Loses 1 mark for each error.
JJJJG
GM = 6.5i – 4j − 5k
3
JJJJG JJJJG
7(ii) AM . GM = 9.75 −16 – 25 = −31.25 M1 Use of x1 x2 + y1 y2 + z1 z2 on AM and GM
JJJJG JJJJG
AM . GM = √(1.5²+4²+5²) × √( 6.5²+4²+5²) cos GMA M1 M1 M1 for product of 2 modulii M1 all correctly connected
Equating → Angle GMA = 121° A1
4
(a) The third and fourth terms of a geometric progression are 48 and 32 respectively. Find the sum to infinity of the progression. [3]
(b) Two schemes are proposed for increasing the amount of household waste that is recycled each week.
Scheme A is to increase the amount of waste recycled each month by 0.16 tonnes.
Scheme B is to increase the amount of waste recycled each month by 6% of the amount recycled in the previous month.
The proposal is to operate the scheme for a period of 24 months. The amount recycled in the first month is 2.5 tonnes.
For each scheme, find the total amount of waste that would be recycled over the 24-month period.
[5]
Scheme A ……
Scheme B ……
Mark scheme
8(a) ar² = 48, ar³ = 32, r = ⅔ or a = 108 M1 Solution of the 2 eqns to give r (or a). A1 (both)
r = ⅔ and a = 108 A1
108 A1 FT Needs correct formula and r between −1 and 1.
S∞ = = 324
1
3
3
8(b) Scheme A a = 2.50, d = 0.16 M1 Correct use of either AP Sn formula.
Sn = 12(5 + 23×0.16)
Sn = 104 tonnes. A1
Scheme B a = 2.50, r = 1.06 B1 Correct value of r used in GP.
=
(
2.5 1.0624 − 1) M1 Correct use of either Sn formula.
1.06 − 1
Sn = 127 tonnes. A1
5
The function f is defined by f x = 2 − 3 cos x for 0 ≤ x ≤ 20.
(i) State the range of f. [2]
(ii) Sketch the graph of y = f x. [2]
The function g is defined by g x = 2 − 3 cos x for 0 ≤ x ≤ p, where p is a constant.
(iii) State the largest value of p for which g has an inverse. [1]
(iv) For this value of p, find an expression for g−1 x. [2]
d2 y
Mark scheme
9(i) −1 ⩽ f(x) ⩽ 5 or [–1, 5] (may use y or f instead of f(x)) B1 B1 –1 < f ( x ) ⩽ 5 or −1 ⩽ x ⩽ 5 or (–1,5) or [5,–1] B1 only
2
9(ii) *B1 Start and end at –ve y, symmetrical, centre +ve.
g(x) = 2 − 3cosx for 0 ⩽ x ⩽ p DB1 Shape all ok. Curves not lines. One cycle [0,2π]
Flattens at each end.
2
9(iii) (greatest value of p =) π B1
1
9(iv) x = 2 − 3cosx → cosx = ⅓(2 – x) M1 Attempt at cosx the subject. Use of cos −1
2− x A1 Must be a function of x,
g−1(x) = cos−1 (may use ‘y =’)
3
2
A curve for which = 2x − 5 has a stationary point at 3, 6. dx2
(i) Find the equation of the curve. [6]
(ii) Find the x-coordinate of the other stationary point on the curve. [1]
(iii) Determine the nature of each of the stationary points. [2]
Mark scheme
10(i) dy B1
integrating → = x² − 5x (+c)
dx
= 0 when x = 3 M1 Uses the point to find c after ∫ = 0.
c=6 A1
x³ 5x² B1 FT Integration again FT if a numerical constant term is
integrating again → y = − + 6x ( +d ) present.
3 2
use of (3, 6) M1 Uses the point to find d after ∫ = 0.
d = 1½ A1
6
10(ii) dy B1
= x² − 5x + 6 = 0 → x = 2
dx
1
10(iii) d²y B1 www
x = 3, =1 and/or +ve Minimum.
dx ²
d²y
x = 2, = −1 and/or −ve Maximum
dx ²
dy B1 www
May use shape of ‘ + x 3 ’ curve or change in sign of
dx SC: x = 3 , minimum, x = 2 , maximum, B1
2
y
3 y=
1 + 4x
P 2, 1
x
O Q
3
The diagram shows part of the curve y = and a point P 2, 1 lying on the curve. The
1 + 4x normal to the curve at P intersects the x-axis at Q.
(i) Show that the x-coordinate of Q is 16
9
. [5]
(ii) Find, showing all necessary working, the area of the shaded region. [6]
Additional Page
If you use the following lined page to complete the answer(s) to any question(s), the question number(s) must be clearly shown.
Mark scheme
11(i) 3 B1
3 × −½ × (1 + 4x ) 2
−
dy 3 B1 Must have ‘× 4’
= 3 × −½ × (1 + 4x ) 2 × 4
−
dx
2 9 M1 Use of m1.m₂ = − 1
If x = 2, m = − , Perpendicular gradient =
9 2
9 M1 Correct use of line eqn (could use y=0 here)
Equation of normal is y − 1 = ( x − 2)
2
16 A1 AG
Put y = 0 or on the line before →
9
5
11(ii) 2
3 3 1 + 4x B1 B1 Correct without ‘÷4’. For 2nd B1, ÷4’.
Area under the curve = ∫ 1 + 4x
0
dx =
1
÷4
2
Use of limits 0 to 2 → 4½ − 1½ M1 Use of correct limits in an integral.
3 A1
2 1
2
9 M1 Any correct method.
Area of the triangle = ½ × 1 ×
9
=
9
or attempt to find ∫ x − 8 dx
16/9
2
1 8 A1
Shaded area = 3 − =2
9 9
6
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Mathematics 9709/11 for May/June 2019 is out of 75 marks, with 1 hour 45 minutes to answer it.
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