factor completely
-3x^2y + 12xy - 12y
x^3 - 9x
3x^4 + 24x^3 + 48x^2
2x^2 - 6x - 56
12x^3 - 9x^2 + 4x - 3
3x^3 - 4x^2 + 9x - 12
-3x^2y + 12xy - 12y = -3y(x^2 - 4x + 4) = -3y(x-2)^2
x^3 - 9x = x(x^2 - 9) = x(x-3)(x+3)
3x^4 + 24x^3 + 48x^2 = 3x^2(x^2 + 8x + 16) = 3x^2(x+4)^2
2x^2 - 6x - 56 = 2(x^2 - 3x - 28) = 2(x-7)(x+4)
12x^3 - 9x^2 + 4x - 3 = 3x(4x^2 - 3x + 1) - 3(4x^2 - 3x + 1) = (3x - 1)(4x^2 - 3x + 1)
3x^3 - 4x^2 + 9x - 12 = x^2(3x - 4) + 3(3x - 4) = (x^2 + 3)(3x - 4)