Question

Given ƒ(x) = 8x − 15, find x when ƒ(x) = 9.

Answer 1

Given f(x) = 9

8x - 15 = 9

8x = 24

∴ x = 3

Check :

f( 3) = 3 * 8 - 15

= 24 - 15

f(3) = 9

Answer 2

`\huge\boxed{x=3}`

First, substitute
`9` for
`f(x)`.

`9=8x-15`

Now, follow the order of operations in reverse. Add
`15` to both sides of the equation.

`9+15=8x-15+15`

`24=8x`

Finally, divide both sides of the equation by
`8`.

`(24)/(8) = (8x)/(8)`

`\boxed{3=x}`