Root of a polynomial

A polynomial is an expression containing a variable x and the standard operations of addition, multiplication and raising to a non-negative integer power. A simple example of a polynomial is

$$7x^2-14x$$

A root of a polynomial is a real number x such that, when we substitute it for the variable x in the polynomial, we get an expression equal to zero. For example, x = 2 is a root of the polynomial above, because substituting 2 for x gives

$$7\cdot 2^2-14\cdot 2$$

which is equal to

$$28-28=0$$

On the other hand, x = 3 is not a root of the polynomial, because substituting it into the polynomial gives

$$7\cdot 3^2-14\cdot 3$$

which is equal to

$$63-42=21$$

We did not get zero, so x = 3 is not a root of the polynomial.

How to find the roots of a polynomial

See linear equations and quadratic equations.