Solve the quadratic equation of the form {eq}ax^2 + bx + c = 0 {/eq} by completing the square.

{eq}x^2 - 20x = 21 {/eq}

Question:

Completing Square of a Quadratic Equation:

We use this method to find a quadratic equation's solution, simplifying a quadratic function, etc., depending on the given condition.

We convert a quadratic equation by rewriting it in the following form of expressions.

{eq}\begin{align*} {\left( {a + b} \right)^2} &= {a^2} + 2ab + {b^2}\\ {\left( {a - b} \right)^2} &= {a^2} - 2ab + {b^2} \end{align*} {/eq}

We add and subtract a particular term on both sides of the equation.

Answer and Explanation: 1