A curve has parametric equations x = t2, y = 3t. State dx/dt and dy/dt.
(Total for Question 9 is 1 mark)
10
A curve satisfies x2 + y2 = 25. Differentiate implicitly with respect to x, giving your answer in the form ... = 0.
(Total for Question 10 is 1 mark)
11
y = (5x + 2)4. Find dy/dx, and hence find the exact value of dy/dx when x = 0.
(Total for Question 11 is 2 marks)
12
y = x e4x. Show that dy/dx can be written as e4x(1 + 4x).
(Total for Question 12 is 2 marks)
13
y = (3x - 1)/(x + 2). Find dy/dx, giving your answer as a single simplified fraction.
(Total for Question 13 is 2 marks)
14
A curve has parametric equations x = t3, y = 2t2, for t in R. Find dy/dx in terms of t.
(Total for Question 14 is 2 marks)
15
A curve has equation y = (4x2 - 3)3.
(a)Find dy/dx, giving your answer in fully factorised form.(2)
(b)Hence find the exact value of dy/dx when x = 1.(2)
(Total for Question 15 is 4 marks)
16
A curve has equation y = x3 e-2x.
(a)Show that dy/dx can be written as x2 e-2x(3 - 2x).(2)
(b)Hence find the exact value(s) of x for which the tangent to the curve is horizontal.(2)
(Total for Question 16 is 4 marks)
17
A curve has equation y = (5x + 1)/(x2 + 3).
(a)Find dy/dx, giving your answer as a single simplified fraction.(2)
(b)Hence find the exact x-coordinates of the points where dy/dx = 0, giving your answers in the form (a ± √b)/c.(2)
(Total for Question 17 is 4 marks)
18
A curve C has equation x2 + y2 + 6x - 4y = 12. Show that dy/dx = -(x+3)/(y-2).
(Total for Question 18 is 3 marks)
19
A curve has parametric equations x = 2t - 1, y = t2 + 3t, for t in R. Find dy/dx in terms of t, and hence find the value of dy/dx when t = 2.
(Total for Question 19 is 3 marks)
20
A cylindrical water tank has a fixed radius of 4 m. Water is pumped into the tank at a constant rate of 6 cubic metres per minute. At time t minutes, the depth of water in the tank is h metres.
(a)Show that dh/dt = 3/(8 π).(2)
(b)Find the time taken, in minutes to 3 significant figures, for the depth to increase from 0 m to 2.5 m.(2)
(Total for Question 20 is 4 marks)
Mark scheme · P14D Pure: Differentiation Depth: Fluency and Exam Drill
Question 1
B1 15(3x-2)4 cao
Answer: 15(3x-2)4
Question 2
B1 6e6x cao
Answer: 6e6x
Question 3
B1 6x(x2+1)2 cao
Answer: 6x(x2+1)2
Question 4
B1 2x ex2 cao
Answer: 2x ex2
Question 5
B1 1/x cao
Answer: 1/x
Question 6
B1 -2/x3 cao
Answer: -2/x3
Question 7
B1 1/(2sqrt(x)) cao
Answer: 1/(2sqrt(x))
Question 8
B1 8 cao
Answer: 8
Question 9
B1 dx/dt = 2t, dy/dt = 3, both required
Answer: dx/dt = 2t, dy/dt = 3
Question 10
B1 2x + 2y(dy/dx) = 0 oe
Answer: 2x + 2y(dy/dx) = 0
Question 11
M1 dy/dx = 20(5x+2)3
A1 at x=0: 160 cao
Answer: dy/dx = 20(5x+2)3; at x=0, dy/dx = 160
Question 12
M1 uses the product rule: dy/dx = e4x + 4x e4x
A1 cso: factorises to e4x(1+4x)
Answer: dy/dx = e4x(1+4x)
Question 13
M1 uses the quotient rule
A1 dy/dx = 7/(x+2)2 cao
Answer: dy/dx = 7/(x+2)2
Question 14
M1 finds dy/dt = 4t and dx/dt = 3t2
A1 dy/dx = 4/(3t) cao
Answer: dy/dx = 4/(3t)
Question 15
(a) M1 applies the chain rule: dy/dx = 3(4x2-3)2 x 8x
(a) A1 24x(4x2-3)2 cao
(a) Answer: dy/dx = 24x(4x2-3)2
(b) M1 substitutes x=1 into the expression from (a)