CONFUSED:
f(x)=3x+1
g(x)=x^2-6

find (fog)(4)

I believe it's 3x^2-17

and then you get
3(4)^2-17
3(16)-17
48-17

31

Very confused though! Don't know if that's the correct way of doing it.

Question

CONFUSED:
f(x)=3x+1
g(x)=x^2-6

find (fog)(4)

I believe it's 3x^2-17

and then you get
3(4)^2-17
3(16)-17
48-17

31

Very confused though! Don't know if that's the correct way of doing it.

dumbcow · Answer

very good, all your steps are correct

dumbcow · Answer

another approach is just plug in the 4 right away into g(x)
--> g(4) = 16-6 = 10

then plug that into f(x)
--> f(10) = 30+1 = 31

anonymous · Answer

learn to trust and check

anonymous · Answer

Thank you! Oh look who it is PG! Haha!

anonymous · Answer

you're doing well!

anonymous · Answer

I'm really confused on these last two though.

anonymous · Answer

that's when you have to trust your methods, step back and make sure things make sense and check your results.  did you see how dumbcow got the answer in 2 different ways?  that will help you to check that you're doing it right.
very good, keep at it!