Question

how do you get 12 and 5 when you factor 3x^2 + 7x - 20? could someone show me how to solve it? thank you

Answer 1

there is a couple ways to do this

Answer 2

one way is to plug it into the quadratic equation

Answer 3

Multiply 3 and -20 to get -60

find two numbers that multiply to -60 and add to 7. These two numbers are 12 and -5

Answer 4

do you know the quadratic equation

Answer 5

3x^2 + 7x - 20
= 3x^2 + 12x - 5x - 20
= 3x(x + 4) - 5(x + 4)
= (x + 4)(3x - 5)

You get 12x and -5x by splitting the middle term 7x since 12 - 5 = 7