Question

factor the polynomial completely. 3x^2 - 11x - 20

Answer 1

(3x +4)(x-5)

Answer 2

i love factoring!! woohoo!!!

Answer 3

It is important to know steps how to do it. It is shown below.
1. The first term is 3x^2. So you need something that will create 3x^2. We get (3x )(x ).
2. Now the last term is -20. So you need something that will result in -20. We need either (-5 and +4) or (-4 and +5).
3. Combine 1 and 2 and we will have 4 options (3x -5)(x +4) or (3x-4)(x+5) or (3x+5)(x-4) or (3x+4)(x-5).
4. Look at the middle term. We need to get -11x.
option 1 (3x*4)+(-5*x) = 12x-5x = 7x --No.
option 2 (3x*5)+(-4*x) = 15x-4x = 11x --No.
option 3 (3x*-4)+(5*x) = -12x+5x = -7x --No.
option 4 (3x*-5)+(4*x) = -15x+4x = -11x --Yes.
5. The answer is (3x+4)(x-5). You can double check :

3x*x =3x^2
(3x*-5)+(4*x) = -11x
4*-5 = -20
= 3x^2-11x-20
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