1.4 Quadratic Equations

Solving a Quadratic Equation: The Square Root Method Example 1 of 1

Example: Solve the quadratic equation with completing the square.

x^2-9=0

The original quadratic equation.
x^2-9=0
Rewrite the quadratic equation so that the square and everything that the square applies to are on one side of the equation.  This is called isolating the square. x^2-9=0
x^2-9+9=0+9
x^2=9
Cancel out the square by square rooting both sides. x^2=9
sqrt{x^2}=sqrt{9}
x=pm 3
The remaining equations are already solved.  The solutions to the equation are 3 and -3. x=-3 or x=3