how do you solve this?

Question

how would you solve each equation by FACTORING?
please show steps


5x^2 - 180 = 0


3x^2 - 16x - 12 = 0

3x(x-1) - 3(2x +1) = 0

Answer 1

5x² - 180 = 0
5(x² - 36) = 0
x² - 36 = 0
(x + 6)(x - 6) = 0
x = 6, or x = -6

3x² - 16x - 12 = 0
(3x + 2)(x - 6) = 0
3x + 2 = 0, x = -2/3
or x = 6

3x(x - 1) - 3(2x + 1) = 0
3x² - 3x - 6x - 3 = 0
3x² - 9x - 3 = 0
3(x² - 3x - 1) = 0
x² - 3x - 1 = 0 [don't think you can factor this further]

Answer 2

5x^2 - 180 = 0
5(x^2 - 36) = 0
x^2 - 36 = 0
x^2 = 36
x = 6; x = -6

3x^2 - 16x - 12 = 0
(3x + 2)(x - 6) = 0
3x + 2 = 0
3x = -2
x = -2/3;
x - 6 = 0
x = 6
so x = 6 or -2/3

3x(x - 1) - 3(2x + 1) = 0
3x^2 - 3x - 6x - 3 = 0
3x^2 - 9x - 3 = 0
x^2 - 3x - 1 = 0
Must use quadratic formula: x = (-b + sq rt (b^2 -4ac)/2a,

a = 1; b = -3; c = -1
so, x = (-(-3) + sq.rt.(-3^2 - 4(1)(-1))/2(1)
x = (3 + sq.rt.(9 +4)/2
x = (3 + sq.rt.(13))/2