I'm so lost on this math Hw it's over factoring variables and I don't get it. Like my teach said that we are supposed to have the number and letter in front of everything.

Question

For example:
-14x^2-7x+21

For factoring I got 7x(-2x-1+3)
Because my teacher told me to to combine both 7 and x. It doesn't come out equally but I'm supposed to have it that way

Answer 1

I did this a few minutes ago

here again
-7 ( 2x + 1 - 3)
-7 (2x+3)(x-1)

Answer 2

But it's supposed to equal to the original equation

Answer 3

It is

Answer 4

(2x +3)(x-1) = 2 x^2 + 1 x - 3

-7 ( 2 x^2 + 1 x - 3)

= -14 x^2 - 7 x + 21