3. Решите уравнение: a) 4²- x²= 0 б) 16-9y² = 0 в) (2−y)²-у(у+2,5)=4

a) $$4^2 - x^2 = 0$$ $$(4-x)(4+x) = 0$$ $$4-x = 0$$ или $$4+x = 0$$ $$x = 4$$ или $$x = -4$$ б) $$16 - 9y^2 = 0$$ $$4^2 - (3y)^2 = 0$$ $$(4-3y)(4+3y) = 0$$ $$4-3y = 0$$ или $$4+3y = 0$$ $$3y = 4$$ или $$3y = -4$$ $$y = \frac{4}{3}$$ или $$y = -\frac{4}{3}$$ в) $$(2-y)^2 - y(y+2.5) = 4$$ $$4 - 4y + y^2 - y^2 - 2.5y = 4$$ $$4 - 6.5y = 4$$ $$-6.5y = 0$$ $$y = 0$$