NESA · HSC Mathematics Advanced · Mixed
HSC Mathematics Advanced practice paper
15 minutes · 10 marks · 4 questions
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1
Differentiate y = x²eˣ.
2 marks -
2
Evaluate ∫₁ᵉ (1/x) dx.
2 marks -
3
The population P of a town grows so that dP/dt = 0.02P. If P = 5000 when t = 0 years, find the population after 10 years, to the nearest whole number.
3 marks -
4
Find the area of the region enclosed between the curve y = x² and the line y = 2x.
3 marks
Mark scheme
1. dy/dx = 2xeˣ + x²eˣ = xeˣ(x + 2). 1 mark for applying the product rule; 1 mark for the simplified result.
2. [ln x]₁ᵉ = ln e − ln 1 = 1. 1 mark for ln x as the primitive; 1 mark for the value 1.
3. P = 5000e^0.02t; P(10) = 5000e^0.2 ≈ 6107. 1 mark for the exponential form; 1 mark for substituting t = 10; 1 mark for 6107.
4. Intersections at x = 0 and x = 2; ∫₀² (2x − x²) dx = 4/3 square units. 1 mark for the intersections; 1 mark for the correct integral; 1 mark for 4/3.
Worked solution · Question 4
Find where the curve and line meet: x² = 2x ⇒ x² − 2x = 0 ⇒ x(x − 2) = 0, so x = 0 or x = 2.
On 0 ≤ x ≤ 2 the line lies above the curve (test x = 1: 2 > 1), so the area is ∫₀² (2x − x²) dx.
= [x² − x³/3]₀² = (4 − 8/3) − 0 = 4/3.
The enclosed area is 4/3 square units.