Answer:
Step-by-step explanation:
1. [tex]y = x^{2} - 2x- 15 = x^{2} - 5x +3x -15 = x(x-5) + 3(x-5) = (x-5)(x+3)[/tex]
2.
[tex]4x^{2} - 8x - 12 = 0\\x^{2} - 2x - 3 = 0\\x^{2} - 3x + x - 3 = 0\\ x(x-3) + 1 (x-3) = 0\\(x-3)(x+1) = 0[/tex]
x= 3 and x = -1
3. [tex]x^{2} - 36 = 0[/tex]
(x-6) (x+6) = 0
x = 6 and -6
