Find f(g(x)) f(x)=4-5x , g(x)=-8x+5

$f (x) = 4 - 5 x$ , $g (x) = - 8 x + 5$

Step 1

Set up the composite result function.

$f (g (x))$

Step 2

Evaluate $f (- 8 x + 5)$ by substituting in the value of $g$ into $f$ .

$f (- 8 x + 5) = 4 - 5 (- 8 x + 5)$

Step 3

Simplify each term.

Apply the distributive property.

$f (- 8 x + 5) = 4 - 5 (- 8 x) - 5 \cdot 5$

Multiply $- 8$ by $- 5$ .

$f (- 8 x + 5) = 4 + 40 x - 5 \cdot 5$

Multiply $- 5$ by $5$ .

$f (- 8 x + 5) = 4 + 40 x - 25$

Step 4

Subtract $25$ from $4$ .

$f (- 8 x + 5) = 40 x - 21$