Вправи: 913

913. Розкладіть на множники:

a) 7x + ay + 7y + ax = (7x + 7y) + (ay + ax) = 7(x + y) + a(y + x) =

= (x + y)(7 + a);

б) (x - 2)² - 1 = (x - 2 - 1)(x - 2 + 1) = (x - 3)(x - 1);

в) 8x³ + 125y³ = (2x)³ + (5y)³ = (2x + 5y)(4x² - 10xy + 25y²);

г) (a + b + c)² - (a - b)² = (a + b + c - a - b)(a + b + c + a + b) =

= c(2a + 2b + c).