Quadratic equations are second-degree algebraic expressions and are of the form \$ax^2 + bx + c = 0\$.

Explanation: A quadratic equation is a second-order polynomial equation in a single variable x.

Example: \$x^2 + 4x + 4\$

The values of the variable that satisfy the equation.

They are also known as the "solutions" or "zeros" of the quadratic equation.

Explanation: Roots of quadratic equation are the values of the variable that satisfy the equation.

Example: \$x^2 + 4x + 4 = 0\$ root is \$x = -2\$.

When \$x = -2\$ is substitued in the equation \$x^2 + 4x + 4 = 0\$ the result is \$0 = 0\$.
So \$x = -2\$ is a root of \$x^2 + 4x + 4 = 0\$.