Помогите решить уравнение

9y-y^2=0

4x^2-25=0

4y-y^3=0

x^2-10x+25=0

1. 9y-y^2=0

y (9-y) = 0

y=0 y=9

2. 4x^2-25=0

(2x) ^2-5^2=0

(2x-5) (2x+5) = 0

x=2/5 x=-2/5

3. 4y-y^3=0

y (4-y^2) = 0

y (2-y) (2+y) = 0

y=0 y=2 y=-2

4. x^2-10x+25=0

x^2-2*x*5+5^2=0

(x-5) ^2=0

x=5