How do you Factor in algebra 2?

for example:
r^2-r-20
and
x^2+8x+12

(r-5)(r+4)

(x+6)(x+2)

Step-by-step explanation:

1 r^2 - 1 r - 20

multiply the first and third terms

-20 times 1 equals -20. take the -1

*what are two numbers that multiply together that equals -20 but add to equal -1?

-5 times 4 equals -20

-5 plus 4 equals -1

(r-5)(r+4)

1 x^2 + 8 x + 12

multiply the first and third terms

12 times 1 equals 12. take the 8

*what are two numbers that multiply together that equals 12 but add to equal 8?

6 times 2 equals 12

6 plus 2 equals 8

=(x+6)(x+2)

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