Let f(x)=2x and g(x) = x^2 +4.
Find (g • f)(-3)

Question

Let f(x)=2x and g(x) = x^2 +4. 
Find (g • f)(-3)

akashdeepdeb · Answer

g(x) = $x^2 + 4$
f(x) = 2$x$

(g o f)(x) = g  (  f(x)  )

Thus,

(g o f)(-3) = g ( f(-3) ) 

Now calculate f(-3).

Let f(-3) = a

Your answer then will be g(a). 

Got it?

anonymous · Answer

So would f(-3) be 2(-3)?

math&ing001 · Answer

Yes @Dreaaaaaa

math&ing001 · Answer

Can you carry on ?

anonymous · Answer

So then the answer for f(x) would be -6 and I have to plug that into g(x)?

math&ing001 · Answer

Exactly !

anonymous · Answer

Okay thank you! I understand now !

math&ing001 · Answer

You're welcome, have a great time at Openstudy !

precal · Answer

is this a composition?  I believe it is times

anonymous · Answer

What do you mean?

precal · Answer

is your dot a "dot product" which means to multiply or it is a hollow dot which means composition.  It does matter because the other responses are for composition but I think it it solid and therefore it means multiplication

anonymous · Answer

No it's not a solid it's an open circle. I just didn't have it on my keyboard :/

precal · Answer

ok then an open circle is composition and the above instructions are correct.