1) 15x + 15y = 15(x + y)
2) 12в³к² + 6в⁴к + 3в⁶к⁵ = 3в³к(4к + 2в + в³к⁴)
3) mn - mt + 2n - 2t = (mn - mt) + (2n - 2t) = m(n - t) + 2(n - t) = (n - t)(m + 2)
4) (а - в)(а + в) + 2(а² - в²) = (а - в)(а + в) + 2(а² - в²) = а² - в² + 2а² - 2в² =
3а² - 3в²
5) 4n² - 4n + 1 = (2n - 1)²
6) 3x³ - 27x = 0 I : 3
x³ - 9x = 0
x (x - 3)(x + 3) = 0
x₁ = 0; x₂ = 3; x₃ = -3
7) (2x + 3)² - (2x - 5)(5 + 2x) = 4x² + 12x + 9 - 4x² - 25 = 12x - 16
x = -0,5
12×(-0,5) - 16 = -22