[tex]\huge\boxed{x=3}[/tex]
First, substitute [tex]9[/tex] for [tex]f(x)[/tex].
[tex]9=8x-15[/tex]
Now, follow the order of operations in reverse. Add [tex]15[/tex] to both sides of the equation.
[tex]9+15=8x-15+15[/tex]
[tex]24=8x[/tex]
Finally, divide both sides of the equation by [tex]8[/tex].
[tex]\dfrac{24}{8} = \dfrac{8x}{8}[/tex]
[tex]\boxed{3=x}[/tex]
Given f(x) = 9
8x - 15 = 9
8x = 24
∴ x = 3
Check :
f( 3) = 3 * 8 - 15
= 24 - 15
f(3) = 9
