3. Решите уравнение: a) x² - 35² = 0 б) 25 - 81y2 = 0 в) (7-y)²-у(у+1,5)=49

a) \[x^2 - 35^2 = 0\] \[x^2 = 35^2\] \[x = \pm 35\] б) \[25 - 81y^2 = 0\] \[81y^2 = 25\] \[y^2 = \frac{25}{81}\] \[y = \pm \frac{5}{9}\] в) \[(7-y)^2 - y(y + 1.5) = 49\] \[49 - 14y + y^2 - y^2 - 1.5y = 49\] \[-14y - 1.5y = 0\] \[-15.5y = 0\] \[y = 0\] **Ответ:** a) \[x = \pm 35\] б) \[y = \pm \frac{5}{9}] в) \[y = 0\]