Question

Need help with f(x) (I'm working it out)
The question is: given f(x) = x - 7 and g(x) = x^2,
find: g(f(4))

I know that I have to work from the inside and find f(x) first, but wouldn't that be f(4)?
f(x) = x - 7 would be 4 - 7 = -3
And then to find g(x) I have g(x^2)= x^2
Finally, I have x^2(3)
I know I did this wrong but I'm not sure where I messed up.

Answer 1

g(f(4)), when you know f(4) = -3 becomes:
g(-3)

so find that.

Answer 2

If you know how to find f(4), you know how to to find g(-3)... plug in -3 in place of x.

Answer 3

Okay, so I would put g(-3) = 3^2 = 9?

Answer 4

Yes.

Answer 5

9 wouldn't be the final answer would it?

Answer 6

g(f(4)) = g(-3) = 9

Answer 7

Or would I plug it back in like:
9(-3)

I just end the problem when I find g?

Answer 8

Look at the steps:

g(f(4)) = g(-3) = 9

Answer 9

Do you see any more possible steps to take?

Answer 10

Don't over-complicate things.

Answer 11

Okay, I think I got it. I am doing online homework and it's asking me for the opposite now:
f(g(4)) so I think I was just making it harder than it was!
Thank you!

Answer 12

f(g(4))

again start from the inside and work outwards.

Answer 13

g(4) = 4^2 = 16
Substitute 16 into f and have 16 - 7 = 9
f(g(4)) = 9

Answer 14

Yes.

Answer 15

Thanks for your help, I understand it a lot more now!