x2 + 7x + 6 = (x + 6) (x + 1)
x2 + 5x + 6 = (x + 2)(x + 3)
x2 + x - 6 = (x + 3)(x - 2)
-x2 + x + 42 = -[x2 - x - 42] = -[x2 - 7x + 6x - 42] = -[x*(x - 7) + 6*(x - 7)] = -(x - 7)*(x + 6)
x2 + 5x - 6 = x2 + 6x - x - 6 = x(x + 6) - 1(x + 6) = (x - 1)(x + 6)
x2+x-6 = (x-2)(x+3) when factored
x2 + 5x + 3 = 9 x2 + 5x - 6 = 0 (x + 6)(x - 1) = 0 x = -6 or x = 1
x2 + 6x = x*(x + 6)
x2+36x+120 (x+6)(x+20)
x2 + 8x + 12 = (x + 6) (x + 2)
x2 + 7x + 9 = 3 ∴ x2 + 7x + 6 = 0 ∴ (x + 6)(x + 1) = 0 ∴ x ∈ {-6, -1}
= -(x - 7)(x + 6)