Find f(g(x)) f(x)=-10x+15 g(x)=7x+9

$f (x) = - 10 x + 15$ $g (x) = 7 x + 9$

Step 1

Set up the composite result function.

$f (g (x))$

Step 2

Evaluate $f (7 x + 9)$ by substituting in the value of $g$ into $f$ .

$f (7 x + 9) = - 10 (7 x + 9) + 15$

Step 3

Simplify each term.

Apply the distributive property.

$f (7 x + 9) = - 10 (7 x) - 10 \cdot 9 + 15$

Multiply $7$ by $- 10$ .

$f (7 x + 9) = - 70 x - 10 \cdot 9 + 15$

Multiply $- 10$ by $9$ .

$f (7 x + 9) = - 70 x - 90 + 15$

Step 4

Add $- 90$ and $15$ .

$f (7 x + 9) = - 70 x - 75$