It is given that f(x) = 3e²ˣ for x ≥ 0, g(x) = (x + 2)² + 5 for x ≥ 0.
- (i)Write down the range of f and of g.[2]
- (ii)Find g⁻¹, stating its domain.[3]
- (iii)Find the exact solution of gf(x) = 41.[4]
- (iv)Evaluate f'(ln4).[2]
Mark scheme
Marking points from the official mark scheme (May/June 2015). The mark or mark type is shown in brackets.
- [B1] Range for f: y ≥ 3
- [B1] Range for g: y ≥ 9
- [M1] attempt to obtain the inverse function
- [A1] Must be correct form
- [B1] for domain
- [M1] correct order
- [DM1] correct attempt to solve the equation
- [M1] dealing with the exponential correctly in order to reach a solution for x
- [A1] Allow equivalent logarithmic forms
- [B1] g'(x) = 6e2x
- [B1] g'(ln 4) = 96
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