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Using Square Roots to Solve Quadratic Equations

Using Square Roots to Solve Quadratic Equations

Author: Rachel Kaplan
Description:

Objectives for this learning packet include
-Review the idea of a square root and what it means
-When given a quadratic equation where b=0, solve using square roots

With a handy lesson, become familiar with square roots and how to use them to solve some basic quadratic equations.

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Tutorial

Basics of Square Roots

Table of Perfect Squares

02 = 0
12 = 1
22 = 4
32 = 9
42 = 16
52 = 25
62 = 36
72 = 49
82 = 64
92 = 81
102 = 100
112 = 121
122 = 144
132 = 169
142 = 196
152 = 225
162 = 256
172 = 289
182 = 324
192 = 361
202 = 400
212 = 441
222 = 484
232 = 529
242 = 576
252 = 625

 

 

Here's a handy table of perfect squares if you need an easy reference. Trust me though, soon you'll have many of these memorized!

Using Square Roots to Solve Quadratic Equations

Examples

Try some of these out on your own, and scroll down when you're complete to view the final answers.

1. x2+6 = 87

2. x2-7 = 71

3. 9x2+3 = 84

4. 5x2+7 = 132

5. Challenge: x(x2+4) = 40x

 

Answers to Examples

1. ±9

2. ±8

3. ±3

4. ±5

5. ±6