Question

For f(x)=3x+1and g(x)=x^2-6, find (fog)(4)

Answer 1

fog is similar to f(g(x))
now, first, apply x=4 into the function of g and use the result to replace with the function of f
f(x^2-6)
f(4^2-6)
f(10)
now apply 10 to the function of f

Answer 2

wait what?

Answer 3

@Zale101

Answer 4

f(g(x)) is another way of saying f composition to g
f(g(x)) and we know that x = 4 right?
so f(g(4))
what's function g
g(x)=x^2-6

so plug that into the composition and since the function of g(x) is g(4), that means that the x-values of g is 4, correct?
f(g(x^2-6))
f(g(4^2-6))

f(16-6)
f(10)
so the function of f has an x value of 10
so plug the x value 10 to the function of f

f(x)=3x+1

(3(10)+1) ?

Answer 5

Plug in 4 for x into g(x)

\(\ g(x) \rightarrow g(4) \)

\(\ g(4) = (4)^2 - 6 \rightarrow 16 - 6 = 10 \)

\(\ g(4) = 10 \)

Now plug that 10 into f(x)

\(\ f(10) = 3(10) + 1 \)

Answer 6

thanks @tHe_FiZiCx99

Answer 7

the letex was good

Answer 8

;) you rock @Zale101

Answer 9

:3

Answer 10

;>

Answer 11

so you'd get 31?

Answer 12

yes

Answer 13

oh okay, thanks a lot! that really helped!

Answer 14

glad it did!

Answer 15

Lol you're welcome ;) ... even though I'm late and didn't see your reply >.>