1) 5x(a - b) + 3y(a - b) = (a - b)(5x + 3y)
2) 2x² + 2xy + 7x + 7y = (2x² + 2xy) + (7x + 7y) = 2x(x + y) + 7(x + y) =
= (x + y)(2x + 7)
3) 15c²d + 12cd² = 3cd(5c + 4d)
1) 5x(a - b) + 3y(a - b) = (a - b)(5x + 3y)
2) 2x² + 2xy + 7x + 7y = (2x² + 2xy) + (7x + 7y) = 2x(x + y) + 7(x + y) =
= (x + y)(2x + 7)
3) 15c²d + 12cd² = 3cd(5c + 4d)