Find f(g(x)) f(x)=3x-9 , g(x)=(x+9)/3

$f (x) = 3 x - 9$ , $g (x) = \frac{x + 9}{3}$

Step 1

Set up the composite result function.

$f (g (x))$

Step 2

Evaluate $f (\frac{x + 9}{3})$ by substituting in the value of $g$ into $f$ .

$f (\frac{x + 9}{3}) = 3 (\frac{x + 9}{3}) - 9$

Step 3

Cancel the common factor of $3$ .

Cancel the common factor.

$f (\frac{x + 9}{3}) = 3 (\frac{x + 9}{3}) - 9$

Rewrite the expression.

$f (\frac{x + 9}{3}) = x + 9 - 9$

Step 4

Combine the opposite terms in $x + 9 - 9$ .

Subtract $9$ from $9$ .

$f (\frac{x + 9}{3}) = x + 0$

Add $x$ and $0$ .

$f (\frac{x + 9}{3}) = x$