Solving Equations by Completing the Square
Videos to help Algebra I students learn how to solve complex quadratic equations, including those with a leading coefficient other than 1, by completing the square. Some solutions may be irrational. Students draw conclusions about the properties of irrational numbers, including closure for the irrational number system under various operations.
New York State Common Core Math Module 4, Algebra I, Lesson 13
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Common Core For Algebra I
Lesson 13 Summary
When a quadratic equation is not conducive to factoring, we can solve by completing the square. Completing the square can be used to find solutions that are irrational, something very difficult to do by factoring.
1. The leading coefficient of x2 must be 1
2. Move the constant (c) so that the
variables are isolated
3. Take half the (b) coefficient. Square it
and add it to both sides
4. Rewrite the equation as perfect square binomial
5. Solve for x
Solve for x:
x2 - 2x = 12
1/2 r2 - 6r = 2
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