Some quadratic equations can be solved by taking the square root. For example: (x - 8)2 = 100 can be solved by first taking the square root of both sides.
When a quadratic cannot be solved by taking the square root, we can complete the square in order to solve.
Completing the square of x2 + bx + c = 0:
Completing the square of x2 + bx + c = 0:
- move c to the opposite side to get x2 + bx = -c
- find the value of b, half it, then square it (b/2)2
- add that value to both sides of the equation
- factor as x2 + bx + (b/2) = (x + b/2)2
Complete the Square to Solve
Completing the Square
