Question

Решите пожалуйста!!

Answer 1

Ответ:

$25x {y}^{2} - 30 {x}^{2} {y}^{3} = 5x {y}^{2} (5 - 6xy)$

$81a - {a}^{3} = a(81 - {a}^{2} )$

${(a + b)}^{2} - {a}^{2} - {b}^{2} = \\ {a}^{2} + 2ab + {b}^{2} - {a}^{2} - {b}^{2} = 2ab$

$3 {a}^{2} {b}^{2} + 9ab + 27 {a}^{2} b = \\ 3ab(ab + 3 + 9a)$

$5y - 2(y - 4) = 7y + 10 \\ 5y - 2y + 8 = 7y + 10 \\ 5y - 2y - 7y = 10 - 8 \\ - 4y = 2 \\ y = \frac{2}{ - 4} = - 0.5$