Question: how to find how many zeros a quadratic function has?
Answer: For y = x^2 - 1, the discriminant equals 0 squared - 4 times 1 times -1 or 0 plus 4. The square root of 4 is both plus 2 and minus 2, so that's why this function has two zeros. For y = x^2 + 1, the discriminant equals 0 squared - 4 times 1 times 1 or 0 minus 4.