# Math Help - Find g for f(g(x)) = 5 + x when f(x) = x^2 + 3

1. ## Find g for f(g(x)) = 5 + x when f(x) = x^2 + 3

Find g for f(g(x)) = 5 + x when f(x) = x^2 + 3

Does anyone know how to find g?

I tried the following:

sqrt(x) results in x + 3 which is wrong...
sqrt(x) + 2 results in x + 4sqrt(x) + 7 which is wrong...
etc...

2. ## Re: Find g for f(g(x)) = 5 + x when f(x) = x^2 + 3

Nevermind, sqrt(x + 2) is the right answer. I finally found it!

3. ## Re: Find g for f(g(x)) = 5 + x when f(x) = x^2 + 3

Originally Posted by Lotte1990
Find g for f(g(x)) = 5 + x when f(x) = x^2 + 3

Does anyone know how to find g?
Can you solve ${y^2} + 3 = 5 + x$ for $y~?$

4. ## Re: Find g for f(g(x)) = 5 + x when f(x) = x^2 + 3

Originally Posted by Lotte1990
Nevermind, sqrt(x + 2) is the right answer. I finally found it!
Looks like g can be the negative of this as well.