\[\boxed{\text{731.}\text{\ }еуроки - ответы\ на\ пятёрку}\]
Пояснение.
Решение.
\[\textbf{а)}\ \text{ax} - y + x - \text{ay} =\]
\[= (x - y)(a + 1)\]
\[\left( \text{ax} + x \right) - \left( \text{ay} + y \right) =\]
\[= (x - y)(a + 1)\]
\[x(a + 1) - y(a + 1) =\]
\[= (x - y)(a + 1)\]
\[(a + 1)(x - y) = (x - y)(a + 1)\]
\[(x - y)(a + 1) = (x - y)(a + 1)\]
\[Тождество\ верно.\]
\[\textbf{б)}\ ax - 2by + ay - 2bx =\]
\[= (a - 2b)(x + y)\]
\[(ax - 2bx) + (ay - 2by) =\]
\[= (a - 2b)(x + y)\]
\[x(a - 2b) + y(a - 2b) =\]
\[= (a - 2b)(x + y)\]
\[(a - 2b)(x + y) =\]
\[= (a - 2b)(x + y)\]
\[Тождество\ верно.\]