When you put the function into your graphing calculator, just make sure you can see the whole window so you can see all the turns. Whenever you see your graph intersects with the x-axis, you have 1 zero... so just go ahead and count how many times it intersects the x-axis.
For example: for a straight line y=2x+3 you get 1 zero. y=6 you get 0 zero and a parabola has 2 zeroes if its two ends intersect the x-axis, but it can also have 1 zero in the case where it's vertex is on the x-axis or 0 zero in the case where the vertex is above or below the x-axis and open in the opposite direction as the x-axis.
How do I know how many possible zeroes of a function there are? I have a graph and i have to find how many zeroes there are.
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I agree with jake1214 on the number of real solutions. However, the total number of solutions (real and complex) will equal the degree of the equation. You cant graph complex functions on most graphing calculators.
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