Easy -1.8 This is a 1-mark multiple choice question requiring only basic inverse function knowledge. Students need to recognize that f(x) = f⁻¹(x) when x lies on the line y=x, or simply find f⁻¹(x) = (x-1)/2 and solve 2x+1 = (x-1)/2 to get x=−1. This is significantly easier than average A-level questions, being purely procedural with minimal calculation.
The function f is defined by
$$f(x) = 2x + 1$$
Solve the equation
$$f(x) = f^{-1}(x)$$
Circle your answer.
[1 mark]
\(x = -1\) \quad\quad \(x = 0\) \quad\quad \(x = 1\) \quad\quad \(x = 2\)
The function f is defined by
$$f(x) = 2x + 1$$
Solve the equation
$$f(x) = f^{-1}(x)$$
Circle your answer.
[1 mark]
$x = -1$ \quad\quad $x = 0$ \quad\quad $x = 1$ \quad\quad $x = 2$
\hfill \mbox{\textit{AQA Paper 3 2022 Q3 [1]}}