Given that ∫₀ᵃ e^(2x) dx = 50, find the exact value of a. You must show all your working.
- (a)Given that ∫₀ᵃ e^(2x) dx = 50, find the exact value of a. You must show all your working.[4]
- (b)(i)Find the equation of the curve.[4]
- (b)(ii)Find ∫ y dx and hence evaluate ∫_π/2^π y dx.[5]
Mark scheme
Marking points from the official mark scheme (May/June 2019). The mark or mark type is shown in brackets.
- [B1] e^(2x)/2 seen
- [M1] e^(2a)/2 - e^0/2 = 50 (Uses limits correctly for their integral and sets = 50)
- [M1] 2a = ln101 oe (Using their integral)
- [A1] a = ln101 / 2 or ln√101 final answer (Allow any exact equivalent)
- [B2] [y =] 3x - (2/5)sin 5x [+c] (B1 for -k sin 5x where k > 0)
- [M1] (8π/2) = 3(π/5) - (2/5)sin(5π/5) + c
- [A1] y = 3x - (2/5)sin 5x + π
- [B3] ∫ y dx = 3x²/2 - (2/25)cos 5x + πx [+c] (B2 for -(2/25)cos 5x oe nfww and B1FT for 3x²/2 + ... + πx [+c])
- [M1] their F(π) - their F(π/2)
- [A1] 16[.0] or 15.95 to 15.96 or 13π²/8 - 2/25
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