SOLUTION: Not sure if I chose the right topic for this question. But this is a college algebra class I am taking right now. Find g(-4) and f(g(-4)). f(x)= x2 - x + 5 g(x)= 2x - 4

Algebra ->  Equations -> SOLUTION: Not sure if I chose the right topic for this question. But this is a college algebra class I am taking right now. Find g(-4) and f(g(-4)). f(x)= x2 - x + 5 g(x)= 2x - 4       Log On


   

Question 1175270: Not sure if I chose the right topic for this question. But this is a college algebra class I am taking right now.

Find g(-4) and f(g(-4)).
f(x)= x2 - x + 5
g(x)= 2x - 4


g(-4) = ?
f(g(-4)) = ?
Found 2 solutions by ewatrrr, Theo:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!

Hi
f(x)= x2 - x + 5
g(x)= 2x - 4
g(-4) = -12    |g(x) = 2x-4  ⇒ g(-4) = 2*-4 - 4 = -12
f(g(-4))  Substitute that -12 value for x in the f(x) function
f(g(-4)) = (-12)^2 +12 + 5 = 161
Wish You the Best in your Studies.


Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
see my worksheet below.



step 1 shows the problem.

step t2 solves for f(g(x)) by replacing x in f(x) with (2x - 4) from g(x).

the result is that f(g(x)) = 4x^2 - 18x + 25.

step t3 replaces x with -4 in f(g(x)) to get the result of 161.

the alternative is to find g(-4) first by replacing x in g(x) with -4 to get -12.

step b2 replaces x in g(x) with -4) to get -12.

step b3 replaces g(-4) in f(g(-4) with -12 to get f(-12) which is equal to 161.

you get 161 either way.

let me know you have any questions about this.

here's a reference on composite functions that you might find informative.

https://www.storyofmathematics.com/composite-functions#:~:text=A%20composite%20function%20is%20generally,)%20and%20g%20(x).