We can factor out a x^2
y = x^2(x + 3)
Solve for 0
0 = x^2(x + 3)
Either x^2 is 0 or (x + 3) is 0.
If (x + 3) is 0 then x = -3
If x^2 = 0 then x= 0 or x = 0 (it's square; there's two roots x*x)
So the roots are: 0, 0, -3. Use both zeros; since it's a cubic expression, there are 3 roots.
