Question

How do you find `f(-1)` given `f(x)=2x+2`?

Answer 1

`f(color(red)(-1)) = 0`

Explanation:

To solve `f(-1)` you need to substitute `color(red)(-1)` for every occurrence of `color(blue)(x)` in the function:

`f(color(blue)(x)) = 2color(blue)(x) + 2`

Giving:

`f(color(red)(-1)) = (2*color(red)(-1)) + 2`

`f(color(red)(-1)) = -2 + 2`

`f(color(red)(-1)) = 0`