Lesson 14 Summary
The quadratic formula is derived by completing the square on the general form of a quadratic equation ax2 + bx + c = 0, where a ≠ 0. The formula can be used to solve any quadratic equation and is especially useful for those that are not easily solved by using any other method (i.e., by factoring or completing the square).
The following diagram shows how to derive the Quadratic Formula. Scroll down the page for more examples and solutions on how to use the quadratic formula to solve equations.
Lesson 14 Problem Set Sample Solutions
Use the quadratic formula to solve each equation.
1. Solve for z. z2 - 3z - 8 = 0
2. Solve for q. q2 -8 = 3q
3. Solve for m. 1/3 m2 + 2m + 8 = 5
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