April 27, 2015

Students derive the quadratic formula by completing the square for a general quadratic equation in standard form, ax^2 + bx + c = 0, and use it to verify the solutions for equations from the previous lesson for which they have already factored or completed the square.

- Mathematics > General
- Mathematics > Algebra

- Grade 9
- Grade 10

Make sense of problems and persevere in solving them.

Reason abstractly and quantitatively.

Model with mathematics.

Use appropriate tools strategically.

Attend to precision.

Look for and make use of structure.

Solve quadratic equations by inspection (e.g., for x² = 49), taking square roots, completing the square, the quadratic formula and factoring, as appropriate to the initial form of the equation. Recognize when the quadratic formula gives complex solutions and write them as a ± bi for real numbers a and b.