Question

Let f(x) = -2x - 7 and g(x) = -4x + 3. Find (f o g)(-5)

A.
23

B.
3

C.
-9

D.
-53

Answer 1

Ok, so let us think about this one. You first evaluate the inside function which is g(x).

Answer 2

g(-5) = -4(-5) + 3

Answer 3

What is that?

Answer 4

After you get the result of g(x), then you can take that and use it in f(x)

Answer 5

This is an example


\(\LARGE\color{blue}{ \bf f(x)=4x+2 }\) AND \(\LARGE\color{blue}{ \bf g(x)=3x-2 }\)

Find fog when x=2?

\(\LARGE\color{blue}{ \bf f(g)x))=4(3x-2)+2 }\)
\(\LARGE\color{blue}{ \bf f(g)x))=12x-8+2 }\)
\(\LARGE\color{blue}{ \bf f(g)x))=12x-6 }\)

\(\LARGE\color{blue}{ \bf f(g)x))=12(2)-6 }\)
\(\LARGE\color{blue}{ \bf f(g)x))=24-6 }\)
\(\LARGE\color{blue}{ \bf f(g)x))=18 }\)

Answer 6

I was just walking him through the problem @SolomonZelman, but showing him an example would help :)

Answer 7

jtryon, you were a little off though. Nice try. Look at my example, and tell me if you see your err.

Answer 8

f(g) not g(x)

Answer 9

Yes, 1st plug in g(x) into the x of f(x), then simplify, and then plug in -5 for x.

Answer 10

Yes, I see it now

Answer 11

thanks everyone :) i have one more

Answer 12

READ CAREFULLY.

you put in for x, into g(x), what the f(x) is equal to.

Answer 13

@jtryon

Answer 14

ok, I see you don't want to try to do the problem. I am out.

Answer 15

i do ido

Answer 16

So do what I told you then...

Answer 17

(-4(-5))+3= 23

Answer 18

23 for each x at f(x) and it will be
(-2(23))-7=-53 so D right?/