# Math Help - composition

1. ## composition

find f * g if f(x) = x^2-7 and g(x) = 2x+4

2. do i combine the two equations?

3. Originally Posted by aikenfan
find f * g if f(x) = x^2-7 and g(x) = 2x+4
It depends.
$(f * g)(x) = (x^2 - 7)(2x + 4)$
if this is multiplication of functions.

If it is composition of functions:
$(f \circ g)(x) = f(g(x)) = f(2x + 4) = (2x + 4)^2 - 7$

-Dan

4. It is this:
(f \circ g)(x) = f(g(x)) = f(2x + 4) = (2x + 4)^2 - 7
but i am a bit confused

5. I think aikenfan asked for $(f\circ{g})$

$(f\circ{g})=f(g(x))=(g(x))^2-7=(2x+4)^2-7$

Which is the same result of Dan