6х-3х^2=0
3х^2-12х=0
7y^2+y=0
4y-y^2=0
х^4-17х^2+16=0
х^4+5^2-36=0
х^4-8^2+16=0
х^4+5x^2+9=0

1)
x(6-3x)=0
[x=0      [x=0
[-3x=-6  [x=2
2)
x(3x-12)=0
[x = 0      [x=0
[3x = 12  [x=4
3)
y(7y+1)=0
[y=0      [y = 0
[7y = -1 [y = -(1/7)
4)
y(4-y)=0
[y = 0
[y = 4