Question

Evaluate the function f (x) = -4x + 9 at f (3).

Answer 1

substituting 3 for x:
-4(3)+9
-12+9
-3

Answer 2

Plug in f(x) = 3 to solve 

$f (x) = -4x + 9 $

$3 = -4x + 9$ 

$3-9=-4x$ 

$-6=-4x$ 

$-6/-4=x$ 

$6/4=x$ 

$3/2=x$ 

$x=3/2$