Question

Please help Factor 3x2 - 12x - 36 completely.

Answer 1

3x^2 - 12x - 36 = 3(x^2 - 4x - 12)

to factor x^2 - 4x - 12, you need to find two numbers that multiply to -12 and add to -4

Answer 2

So would it be 3(x+4)(x-3) ?

Answer 3

4 times -3 is -12

but 4 plus -3 is not -4

Answer 4

I'm a little confused.

Answer 5

which factors of -12 also add to -4 ?

Answer 6

oh 6 and 2?

Answer 7

example: -1 and 12 multiply to -12 but they don't add to -4

Answer 8

close

Answer 9

Im just confused because my options are 3(x-6)(x+2) , (3x+6)(x-2) , 3(x+4)(x-3) and (3x-4)(x+3) so I dont understand if it 3 and 4 dont work into that and 6 and 2 dont either?

Answer 10

well it's not 6 and -2 since 6 plus -2 = +4

it's actually -6 and 2 because -6 plus 2 = -4

Answer 11

so x^2 - 4x - 12 factors to (x-6)(x+2)

Answer 12

3x^2 - 12x - 36 = 3(x^2 - 4x - 12)

3x^2 - 12x - 36 = 3(x-6)(x+2)

Answer 13

Oh okay that makes more sense

Answer 14

could you help me with another question

Answer 15

sure