Page 12 - ACE YR IGCSE A TOP APPR' TO ADD MATH

(c) The function f(x) = x + 4x + 9 has a domain set of all real numbers.
2
Find the range of f.

[1]

(d) Explain why f has no inverse with its given domain. Suggest a domain for f for which it
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has an inverse.

[2]

18. The function f is defined by f(x) = 2x − 1 for x  R.
−1
(a) Sketch in a single diagram y = f(x) and y = f (x).
y

x

[3]

(b) The function g is defined by g(x) = −x − 2x for x  R.
2
Express gf(x) in terms of x and find the maximum value of gf(x).

[3]

Chapter 1 Functions 9

Chapter 1 Add Math (1 to 12).indd 9 14/03/2022 12:16 PM