Can someone help me with composing two polynomial functions?
F(x)=x^2+4. g(x)=x-5.
(f*g)(x)=?

Question

Can someone help me with composing two polynomial functions?
F(x)=x^2+4.             g(x)=x-5. 
(f*g)(x)=?

danjs · Answer

the product of two functions.

(f * g)(x)  =  f(x) * g(x)

sunnnystrong · Answer

What @DanJS  said...

f composed with g -->
$$f(x-5)$$
$$(x-5)^2+4$$

flowers · Answer

Oh okay basically substitutions 
I dont like functions makes my brain crazy

danjs · Answer

yeah , just multiply them together

sunnnystrong · Answer

... wait, is this supposed to be 
f circle g 
or
f*g?

danjs · Answer

(f*g)(x) = f(x) * g(x)  =  (x^2 + 4)*(x - 5) = ...

flowers · Answer

Circle

danjs · Answer

thats not multiply, open circle is composition function  f(g(x))

sunnnystrong · Answer

Oh okay cool.
Yep you just compose your function -->
If it was g circle f what would it be?

sunnnystrong · Answer

yea idk @DanJS XD

flowers · Answer

Oops i didnt notice a circle button my computer

sunnnystrong · Answer

DW about it hahaha... but what would
g composed with f look like? @flowers

danjs · Answer

the f is first,  it is 'f of g'


f[g(x)]

flowers · Answer

Im not sure but 
X^2+4-x-5

sunnnystrong · Answer

@DanJS is right... so this is different. (f circle g does not equal g circle f ) just to be clear... It is all basically substitution like you said :D ^^ See earlier comment
@flowers

If:
F(x)=x^2+4.
G(x)=x-5.

G(x^(2)+4)
(x^(2)+4)-5
=x^(2)-1

flowers · Answer

Cool thanks 
Thanks for your help

sunnnystrong · Answer

NP :D Always happy to help!