The Quadratic Formula Worksheets

How to solve it: a worked example

Solve with the quadratic formula. Round to the nearest hundredth when the roots aren't exact.

1. Startx² + 7x − 8 = 0
2. Discriminantb² − 4ac = 7² − 4(1)(−8) = 81
3. Quadratic formulax = −7 ± √812(1)
4. Thenx = 1 or x = −8
5. Answerx = 1 or x = −8

Common mistakes to watch for

• Dropping the sign of b: with b = −5, −b is +5.
• Dividing only the square root by 2a instead of the whole numerator.
• Writing b² − 4ac as −4ac when b is negative: (−3)² is 9, not −9.

Tip: tick “Step-by-step answer key” in the generator to print each step for marking.