1) (x + 7) (y + 5) = + + +
2) ( + a) ( + 2) = 3b + 6 + ab +
3) (x + ) ( + 2) = xy + + 4y + 8
4) (11 - b) (2 - c) = 22 11c 2b bc
5) (x - 3) (4x - 7) = - - + = 4x² - + 21
6) (10a - 25b) (3b + 2a) =
= 20a² + 75b²