| x | -2 | -1 | 0 | 1 | 2 |
| y="x3-x2" | -12 | -2 | 0 | 0 | 4 |
| (x,y) | (-2,-12) | (-1,-2) | (0,0) | (1,0) | (2,4) |
In y = x3 you can see that 0 (zero) is the x-coordinate of the only point where the graph of y = x3 intersects the X-axis. So, the polynomial has only one zero. Similarly, 0 and 1 are the -coordinates of the only points where the graph of y = x3 - x2 intersects the X-axis. So, the cubic polynomial has two distinct zeroes.
From the examples above, we see that there are at most 3 zeroes for any cubic polynomial.In other words, any polynomial of degree 3 can have at most three zeroes.