Question

If f(x)= 2x+4, and g(x)= (x^2+x+5), find g(f(x))

Answer 1

g(x) = x^2+x+5
To find g(f(x)), replace x with f(x) on the right hand side.
g(f(x)) = { f(x) }^2 + f(x) + 5
put f(x) = 2x + 4 above to get g(f(x)).

Answer 2

so I have (2x+4)^2+2x+4+5... is that right so far?

Answer 3

Yes. Expand (2x+4)^2 and simplify.

Answer 4

okay so I get to 4x^2-14x+25... should i factor that or is that the answer?

Answer 5

Everything is positive before and so there shouldn't be a negative after the simplification.

Answer 6

oops so 4x^2+18x+25?

Answer 7

Yes. And it is non-factorable due to negative discriminant and so you can leave it like that.

Answer 8

okay, Thanks for the help!

Answer 9

You are welcome.