Question

Using complete sentences, explain how to completely factor 2x2 − 8x − 42

Answer 1

do you know what the greatest number that will go into all of these numbers is?

Answer 2

2(x+3)(x-7)

Answer 3

2

Answer 4

yeah

Answer 5

So how do you solve it?

Answer 6

you just look for the # that could be the factor for the equation.

Answer 7

But how did you get 2(x+3)(x-7)?

Answer 8

Ok. THis is what @esbenda.idoris did. First, you have to factor out the GCF or Greatest Common Factor which as you said is 2.
\[2(x^2 - 4x - 21)\]Now, what are 2 factors of -21 that add up to -4?

Answer 9

uhmm i dont know.

Answer 10

How about -7 and 3? Do you think they work?

Answer 11

yes

Answer 12

Alright. Now, place them like this.
\[2(x - 7)(x + 3)\]Do you see now?

Answer 13

yes, thank you.

Answer 14

Glad to help :)