Question

Factor x2 – 7x + 12.
(x – 3)(x + 4)
(x – 3)(x – 4)
(x – 6)(x – 2)
(x – 1)(x – 12)
Please explain how to do this

Answer 1

when you factor, you are trying to find two number that you multply to get a number(in this case +12) that add together to get, in this case, -7x

Answer 2

so factors of 12 are?
1 and 12
2 and 6
3 and 4
out of those pairs, which add up to be 7?

Answer 3

3 and 4

Answer 4

alright, so the form for factoring is
(x )(x )
so since you know that 3 and 4 will be your numbers you can plug those in
(x 3)(x 4)
now you have to determine the signs.

Answer 5

How do you determine the signs?

Answer 6

determining signs in some cases are a guessing game

Answer 7

easiest way is thinking that you need to have a negative 7

Answer 8

so -3+-4 gives you -7

Answer 9

and also -3*-4 gives you +12

Answer 10

well, in this case, since you know that the 12 is positive but the 7 is negative, you would make them both negative because when you multiply, 2 negatives creata a positive.