3. Решите уравнение: a) 4²-x²=0 6) 81у²- 16 = 0 в) (9-x)² - x(x+8,5)=81

Ответ:

1. a) $$4^2 - x^2 = 0$$ $$(4 - x)(4 + x) = 0$$ x = 4, x = -4
2. б) $$81y^2 - 16 = 0$$ $$(9y - 4)(9y + 4) = 0$$ y = \frac{4}{9}, y = -\frac{4}{9}
3. в) $$(9 - x)^2 - x(x + 8.5) = 81$$ $$81 - 18x + x^2 - x^2 - 8.5x = 81$$ $$-18x - 8.5x = 0$$ $$-26.5x = 0$$ x = 0

Ответ: а) x = 4, x = -4, б) y = 4/9, y = -4/9, в) x = 0