36 (х + 3)² - х² = (6(x + 3))² - x² = (6x + 18)² - x² = (6x + 18 - x)(6x + 18 + x) = (5x + 18)(7x + 18)
ас² - bc² - bc + ac - a + b = c² (a - b) - c (a - b) - (a - b) = (c² - c - 1)(a - b)
3x² + 10x - 8 = 3 (x - 2/3)(x + 4) = (3x - 2)(x + 4)
3x² + 10x - 8 = 0
D = 10² - 4 * 3 * (- 8) = 196
x₁ = (- 10 + √196) : (2 * 3) = 2/3
x₂ = (- 10 - √196) : (2 * 3) = - 4