x^2 + 4x - 12 = 0 since we have -12, its factors are with different sign;
(x + )(x - ) = 0
since we have 4x, that means that factors are 6 and 2, and 6 will be positive, so we have:
(x + 6)(x - 2)= 0
x = -6 or x = 2
(check)
(4x + 5)(x - 3)
x2 - 4x - 21 = (x-7)(x+3)
4(x - 1)(x + 1)
2(x - 1)(2x + y)
4(x+y)^2
4(x^2 + x + 3)
x(x-4)
(4x - 7y)(4x + 7y)
I assume you wanted this factored: (x+6)(x-2)
(4x + 5)(x - 3)
No
x2 - 4x - 21 = (x-7)(x+3)
2(x^2 + 2)(x + 3)
4(x - 1)(x + 1)
4*x*x*6*x
2(x - 1)(2x + y)
4(x+y)^2