A-LevelMathematicsFunctions9709/12 · Oct/Nov 2021 · Q35 Marks
The function f is defined as follows: f(x) = (x + 3)/(x - 1) for x > 1.
- (a)Find the value of ff(5).[2]
- (b)Find an expression for f⁻¹(x).[3]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.
- [M1] Clear evidence of applying f twice with x = 5.
- [A1] 5
- [*M1] Setting f(x) = y or swapping x and y, clearing of fractions and expanding brackets. Allow ± sign errors.
- [DM1] Finding x or y = . Allow ± sign errors.
- [A1] (x+3)/(x-1) OE e.g. 1 + 4/(x-1) etc. Must be a function of x, cannot be x = .
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