Question

Given the function f(x) = 2x, find the value of f−1(16)

Answer choices

A) f−1(16) = 4
B) f−1(16) = 8
C) f−1(16) = 32
D) f−1(16) = 65,536

Answer 1

f(x) = 2x
x = f(x) / 2

f-1(x) =  x/2

so f-1(16) =  8

Its B

Answer 2

ANSWER

${f}^{ - 1} (16) = 8$
EXPLANATION


The given function is

$f(x) = 2x$

We need to determine the expression for
${f}^{ - 1} (x)$

So we first of all let,

$y = f(x)$

This implies that,

$y = 2x$


We interchange x and y to get,

$x = 2y$


We now make y the subject to obtain,

$\frac{x}{2} = y$

Or

$y = \frac{x}{2}$

This is the inverse function,


${f}^{ - 1} (x) = \frac{x}{2}$

This implies that,

${f}^{ - 1} (16) = \frac{16}{2}$


${f}^{ - 1} (16) = 8$


The correct answer is B.