State the range of f.
- (a)(i)State the range of f.[1]
- (a)(ii)Find f⁻¹ and state its domain.[4]
- (b)It is given that g(x) = x² + 5 and h(x) = lnx for x > 0. Solve hg(x) = 2.[3]
Mark scheme
Marking points from the official mark scheme (May/June 2017). The mark or mark type is shown in brackets.
- [B1] f>5, f(x)>5
- [B1] y-5 = e-4x or x-5 = e-4y
- [B1] -4x = ln (y-5)/3 or -4y=ln(x-5)/3
- [B1] leading to f⁻¹(x) = -1/4 ln ((x-5)/3) or f⁻¹(x) = 1/4 (ln3 - ln(x-5)) or f⁻¹(x) = -1/4 (ln(x-5) - ln3)
- [B1] Domain x > 5
- [B1] ln(x² + 5) = 2
- [B1] x² +5 = e²
- [B1] x=1.55 or better or √e² -5
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