Worked example
x² + 6x − 7 = 0
- Move the constant: x² + 6x = 7.
- Add 9 to both sides: x² + 6x + 9 = 16.
- Rewrite: (x + 3)² = 16.
- Take both square roots: x + 3 = ±4, so x = 1 or x = −7.
Math guide
Build a perfect square deliberately.
Rewrite a quadratic as a perfect square without changing its solutions.
For x² + bx, add (b/2)² to form (x + b/2)². Add the same amount to both sides, then use square roots and remember both signs.
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