Question

Let f(x) = -4x + 7 and g(x) = 10x - 6. Find f(g(x)).
A. -40x + 24
B. -40x + 31
C. -40x + 64
D. -40x + 70

Answer 1

@Loser66 not quite sure how to find f(g(x)). can you help?

Answer 2

\(f(\color{red}{x}) = -4\color{red}{x} +7\)
so that , to find \(f(\color{blue}{g(x)})\)
You just replace \(\color{red}{x}\) by \(\color{ blue}{g(x)}\)

Answer 3

show your try

Answer 4

f(10x-6)=-4x+7
10xf-6f=-4x+7

Answer 5

why do you just replace x by g(x) on the left hand side? How about the right hand side?

Answer 6

Oh okay sorry. Hold on.

Answer 7

I got 10xf-6f=-40x+31

Answer 8

@Loser66 so I guess that answer would be B, right?

Answer 9

yup but
the left hand side, just let it there. I mean f(g(x)) = -40x +31
Don't replace g(x) there. YOu are not wrong, just answer directly to the question : "What is f(g(x) "
got me?

Answer 10

No, I don't understand...

Answer 11

f(g(x)) = f(10x -6) = -4(10x-6) +7 = -40x +31
YOur calculating is correct. Just NOTATION,
To make it clearer,
for example, if you are a son of Michael and your name is Vera. Instead of call you " The son of Michael" , people call you Vera.
Exactly this situation, instead of f ( 10x-6) and you have the name of 10x -6 is g(x), so you just call it f (g(x)) , and calculate it as above

Answer 12

Ohh ok thanks! I get it now :)

Answer 13

:)