Question

Find x if f( x ) = 2 x + 7 and f( x ) = -1

Isn't the answer 5?

Answer 1

It would actually be -4.

Since f(x) = -1 and f(x) = 2x + 7, you would set them equal to each other like so:

-1 = 2x + 7
-8 = 2x
x = -4

The way you did it would be correct if you were trying to find f(x) when
x = -1.

Happy to help!

Answer 2

Yes! Your answer would be 5.

Explanation:

Well, to start, you must plug/substitute -1 in. Sooo...

f( x ) = 2 x + 7

f(-1) = 2(-1) + 7

f(-1) = -2 + 7

f(-1) = 5

I'm really really sorry if this is incorrect...