Question

Розкласти на множики:
7ab+21a-7b-21

Answer 1

$7ab+21a-7b-21=7a(b+3)-7(b+3)=(7a-7)(b+3)$

Answer 2

Ответ:

7(a-1)(b+3)

Объяснение:

7ab+21a-7b-21 = (7ab+21a)-(7b+21) = 7a(b+3)-7(b+3) = (7a-7)(b+3) = 7(a-1)(b+3)