composite functions

Hello,

I've done this question but i am not sure if its correct.

Given that f(x)= 2x+1 and g(x)=3x-5 find the value of

a) fg(0) b) gg(4)

---Answer---

a) fg(0)= f(g(0))

g(0)= 3(0)-5

= - 2

f(-2)= 2(-2)+1

=-3

b) gg(4)= g(g(4))

g(4)= 3(4)-5

=7

f(4)= 2(7)+1

=15

Is my way and answer correct?

Thanks.

Quote:

---

Originally Posted by Oasis1993

Hello,

I've done this question but i am not sure if its correct.

Given that f(x)= 2x+1 and g(x)=3x-5 find the value of

a) fg(0) b) gg(4)

---Answer---

a) fg(0)= f(g(0))

g(0)= 3(0)-5 <=== 0 - 5 = -5

= - 2 <===-5

f(-2)= 2(-2)+1 <=== f(-5) = 2(-5) + 1

=-3 <=== = -9

b) gg(4)= g(g(4))

g(4)= 3(4)-5

=7

f(4)= 2(7)+1 <==== your problem b) says g(g(4)), not f(g(4)). If g(4) = 7, then g(7)=3(7)-5 or 16.

=15

Is my way and answer correct?

Thanks.

---

Hi Oasis1993,

See corrections in red.

Ive made some careless mistakes.
Thanks for your help!

And please try to distinguish better between the product of two functions, fg, and the composition fog or gof.