A-Level Maths H1 Quiz - Calculus (Answer Key)
Total Marks: 50
Topic: Calculus (Differentiation & Integration)
Section A: Differentiation Basics
Q1. [2 marks]
f(x)=4x3−2x+7
f′(x)=12x2−2
Teaching note: Power rule: dxd(xn)=nxn−1. Constant 7 differentiates to 0.
Marking: 1 mark for 12x2, 1 mark for −2.
Q2. [2 marks]
y=e2x⇒dxdy=2e2x
Teaching note: Derivative of ekx is kekx (chain rule with inner 2x).
Marking: 1 mark for e2x, 1 mark for coefficient 2.
Q3. [2 marks]
g(x)=ln(3x)
g′(x)=3x1⋅3=x1
Teaching note: dxdln(u)=u1⋅u′. Here u=3x,u′=3.
Marking: 1 mark for 3x1⋅3, 1 mark for simplified x1.
Q4. [3 marks]
y=(2x+1)5
Let u=2x+1, y=u5
dudy=5u4, dxdu=2
dxdy=5(2x+1)4⋅2=10(2x+1)4
Teaching note: Chain rule: dxdy=dudy⋅dxdu.
Marking: 1 mark chain rule setup, 1 mark derivative of outer, 1 mark final answer.
Q5. [3 marks]
h(x)=5ex−x−2
h′(x)=5ex−(−2)x−3=5ex+x32
Teaching note: Rewrite x21=x−2; power rule gives −2x−3.
Marking: 1 mark for 5ex, 1 mark for +2x−3, 1 mark neat form.
Section B: Tangents and Stationary Points
Q6. [3 marks]
y=x2+3x, y′=2x+3
At x=1: y=4, gradient m=5
Equation: y−4=5(x−1)⇒y=5x−1
Marking: 1 mark derivative, 1 mark point, 1 mark equation.
Q7. [2 marks]
y=ex+2x, y′=ex+2
At x=0: y′=1+2=3
Marking: 1 mark derivative, 1 mark substitution.
Q8. [4 marks]
y=x2−6x+5
y′=2x−6=0⇒x=3
y=9−18+5=−4 → (3, -4)
y′′=2>0 → minimum
Marking: 1 mark derivative, 1 mark x, 1 mark y, 1 mark nature.
Q9. [5 marks total]
(a) [1] f′(x)=3x2−6x
(b) [2] 3x2−6x=0⇒3x(x−2)=0⇒x=0,2
(c) [2] f′′(x)=6x−6; at x=0, f′′=−6<0 max; at x=2, f′′=6>0 min.
Teaching note: Second derivative test: negative = max, positive = min.
Q10. [3 marks]
From graph: f′(x)=0 at local max and min → x=1,3.
f′(x)>0 where curve increasing → x<1 and x>3.
Marking: 1 mark x-values, 2 marks intervals correct.
Image note: Expected curve with max (1,3), min (3,-1); horizontal tangents there.
Section C: Integration Basics
Q11. [2 marks]
∫(3x2−4x+1)dx=x3−2x2+x+C
Marking: 1 mark terms, 1 mark +C.
Q12. [3 marks]
∫02(2x+3)dx=[x2+3x]02=(4+6)−0=10
Marking: 1 mark integral, 1 mark sub, 1 mark answer.
Q13. [2 marks]
∫e3xdx=31e3x+C
Marking: 1 mark coefficient, 1 mark +C.
Q14. [3 marks]
∫(4x+2)3dx, let u=4x+2, du=4dx
=41⋅4(4x+2)4+C=16(4x+2)4+C
Marking: 1 mark substitution, 1 mark power, 1 mark constant.
Q15. [2 marks]
GC: ∫13exdx=e3−e1≈20.086−2.718=17.368
Marking: 1 mark GC use, 1 mark 3 dp.
Section D: Applications
Q16. [4 marks]
Distance = ∫03(6t−2)dt=[3t2−2t]03=27−6=21 units
Marking: 1 mark setup, 1 mark integral, 1 mark eval, 1 mark answer.
Q17. [4 marks]
Intersect x2=4⇒x=±2; with y-axis use x=0 to x=2
Area = ∫02(4−x2)dx=[4x−x3/3]02=8−8/3=16/3
Marking: 1 mark limits, 1 mark integrand, 1 mark eval, 1 mark answer.
Q18. [6 marks total]
(a) [2] x2−4=x+2⇒x2−x−6=0⇒(x−3)(x+2)=0⇒x=3,−2
(b) [4] Area = ∫−23[(x+2)−(x2−4)]dx=∫−23(−x2+x+6)dx
=[−x3/3+x2/2+6x]−23=(−9+4.5+18)−(8/3+2−12)=13.5−(−7.667)=21.167=125/6
Marking: 2+4 as above.
Q19. [4 marks]
(a) [2] P′(x)=100−2x; at x=10, P′=80 (thousand per unit)
(b) [2] 100−2x=0⇒x=50 maximises (since P′′=−2<0)
Marking: 2 each part.
Q20. [5 marks]
(a) [3] dtdP=0.05P⇒∫P1dP=∫0.05dt⇒lnP=0.05t+c
P=Ae0.05t, P(0)=2000⇒A=2000, so P(t)=2000e0.05t
(b) [2] P(10)=2000e0.5≈2000×1.6487=3297
Marking: 3 for (a) steps, 2 for (b) value.