Question

Let f(x)=2x+3, k(x)=x^2+2x-3
Find (f o k)(x)=?

Answer 1

@ranga

Answer 2

Anywhere you see x in k(x), put 2x+3.

Answer 3

So like 2x+3^2+2(2x+3)-3
6x+12
?

Answer 4

Almost there. You made a mistake by not squaring (2x+3). You squared only 3.

Answer 5

I just need to add the ()? right?
4x^2+16x+12?

Answer 6

Yeah, that's all.

Answer 7

Wait stop.

Answer 8

uh oh

Answer 9

I read the question wrong; you're meant to put x^2+2x-3 anywhere you see x in f(x).
So it's just the reverse.
If you were asked to find (k o f)(x). then you'd do what I showed earlier.

Answer 10

Do you understand?

Answer 11

2x^2+4x-3?

Answer 12

Yeah, good job.

Answer 13

Thanks!!!!

Answer 14

You're easy to teach. Keep it up.

Answer 15

Thank you so much for your help!