Algebra 2 Question, I give best answer!!?

Question

Hello, 
I'm not sure how to do this problem. If you could explain and answer how to solve it would be great! Thanks 
If f(x)= 3x^2+5x-9 and g(x)= -2x, find the following composition. 
(f*g)(-2) 
(f*g)(-2)=______

Answer 1

The functions are f(x) = 3x^2 + 5x - 9 and g(x) = - 2x.

To find (f * g)(- 2) = f(- 2) * g(- 2)

= [ 3(- 2)^2 + 5(- 2) - 9 ] * [ - 2(- 2) ]

= [ 12 - 10 - 9 ] * [ 4 ]

= [ 12 - 19 ] * 4

= - 7 * 4

= - 28.

Therefore, (f * g)(- 2) = - 28.

Answer 2

The functions are f (x ) = 3x ² + 5x - 9 and g (x ) = - 2x.

( f o g )(-2 ) = f ( g (-2 ))

Substitute the expression for functioning g  (in this case -2x ) for g (x ) in the composition.

g (-2 ) = -2(-2) = 4

f ( g (-2 )) = f ( 4 )

Substitute the expression for functioning f  (in this case 3x ² + 5x - 9 ) for f (x ) in the composition.

f (x ) = 3x ² + 5x - 9

f (4 ) = 3(4) ² + 5(4) - 9 = 48 + 20 - 9 = 59

( f o g )(-2 )  = 59.