Question

The function f is defined by f(x)=2x² -1.
Find f(2x).

Answer 1

Answer:

$8x^{2} - 1$

Explanation:

$f(x) = 2 {x}^{2} - 1 \\ plug \: x = 2x \\ f(2x) = 2 {(2x)}^{2} - 1 \\ f(2x) = 2 \times 4x^{2} - 1 \\ f(2x) = 8x^{2} - 1$