Polynomial root

The root of a polynomial f is a value for x where the polynomial value f(x) is zero.

For example, if the polynomial $f (x) = 2 x^{2} + 10 x - 28$ then $f (2) = 2 \cdot 2^{2} + 10 \cdot 2 - 28 = 0$ , so 2 is a root of this polynomial.

In fact, it can be seen that also -7 is a root of this polynomial.