Question

Let F(x)= 4 + 5x and g(x) = 2x-1. Find f(g(x)) and g(f(x))
f(g(x))

Answer 1

f(g(x)) means you plug in the function g(x) wherever there is an x in f(x) so we have \[f(g(x)) = 4+(2x-1)\] now evaluate

Answer 2

\[f(g(x)) = 4+5(2x-1)\]

Answer 3

f(2x-1)=4+10x-5

Answer 4

Similarly with g(f(x)) you plug in f(x) in function g(x)

Answer 5

\[g(f(x))=2(4+5x)-1\]

Answer 6

@Astrophysics right?

Answer 7

Yes but we should have left @nabiladh do that on their own to see if they understood the problem :)

Answer 8

yes right,sorry if i done wrong i would delete it

Answer 9

f(2x-1)=10x-1

Answer 10

Nope, what is 2*4?

Answer 11

my bad (8+10x)-1

Answer 12

Yeah now keep simplifying

Answer 13

-8-10x?

Answer 14

2(4+5x)-1 = 8+10x-1 = 10x+7

Answer 15

so f(g(x)) equals 10x+7?

Answer 16

No...that's g(f(x))

Answer 17

Ok I think there's a lot of confusion because both were done at the same time so f(g(x)) is \[f(g(x)) = 4+5(2x-1) = 4+10x-5 = 10x-1\]

Answer 18

Then g(f(x)) is \[g(f(x)) = 2(4+5x)-1 = 8+10x-1 = 10x+7\]

Answer 19

@Astrophysics i see now thanks confusing but i got it

Answer 20

Ok cool :)

Answer 21

f(g(x) = 4 + 5(2x-1) = 4 + 10x - 5 = 10x - 1. g(f(x))= 2(4+5x) - 1 = 8+10x-1 = 10x+7