ГДЗ по алгебре 7 класс Макарычев ФГОС Задание 833

\[\boxed{\text{833.}\text{\ }еуроки - ответы\ на\ пятёрку}\]

\[\textbf{а)}\ (x - 3)^{2} + x \cdot (x + 9) = x² -\]

\[- 6x + 9 + x^{2} + 9x = 2x^{2} +\]

\[+ 3x + 9\]

\[\textbf{б)}\ (2a + 5)^{2} - 5 \cdot (4a + 5) =\]

\[= 4a^{2} + 20a + 25 - 20a -\]

\[- 25 = 4a²\]

\[\textbf{в)}\ 9b(b - 1) - (3b + 2)^{2} =\]

\[= 9b^{2} - 9b -\]

\[- \left( 9b^{2} + 12b + 4 \right) =\]

\[= 9b^{2} - 9b - 9b^{2} - 12b - 4 =\]

\[= - 21b - 4\]

\[\textbf{г)}\ (b - 4)^{2} + (b - 1)(2 - b) =\]

\[= b^{2} - 8b + 16 + 2b - b^{2} -\]

\[- 2 + b =\]

\[= - 5b + 14\]

\[\textbf{д)}\ (a + 3)(5 - a) - (a - 1)^{2} =\]

\[= 5a - a^{2} + 15 - 3a -\]

\[- \left( a^{2} - 2a + 1 \right) =\]

\[= 2a - a^{2} + 15 - a^{2} + 2a -\]

\[- 1 = - 2a^{2} + 4a + 14\]

\[\textbf{е)}\ (5 + 2y)(y - 3) -\]

\[- (5 - 2y)^{2} = 5y - 15 + 2y^{2} -\]

\[- 6y - \left( 25 - 20y + 4y^{2} \right) =\]

\[= - y - 15 + 2y^{2} - 25 + 20y -\]

\[- 4y^{2} = - 2y^{2} + 19y - 40\]