Transcript
Page 1: Solving Absolute Value Equations & Inequalities

Solving Absolute Solving Absolute Value Equations & Value Equations &

InequalitiesInequalitiesSolving Solving Absolute Absolute

Value Value Equations & Equations & InequalitiesInequalities

MM2A1c. Solve absolute value equations and inequalities analytically, graphically, and by

using appropriate technology.

Page 2: Solving Absolute Value Equations & Inequalities

Absolute Value (of x)

• Symbol lxl

• The distance x is from 0 on the number line.

• Always positive

• Ex: l-3l=3

-4 -3 -2 -1 0 1 2

Page 3: Solving Absolute Value Equations & Inequalities

Ex: x = 5

• What are the possible values of x?

x = 5 or x = -5

Page 4: Solving Absolute Value Equations & Inequalities

To solve an absolute value equation:

ax+b = c, where c>0

To solve, set up 2 new equations, then solve each equation.

ax+b = c or ax+b = -c

** make sure the absolute value is by itself before you split to solve.

Page 5: Solving Absolute Value Equations & Inequalities

Ex: Solve 6x-3 = 15

6x-3 = 15 or 6x-3 = -15

6x = 18 or 6x = -12

x = 3 or x = -2

* Plug in answers to check your solutions!

Page 6: Solving Absolute Value Equations & Inequalities

Ex: Solve 2x + 7 -3 = 8

Get the abs. value part by itself first!

2x+7 = 11

Now split into 2 parts.

2x+7 = 11 or 2x+7 = -11

2x = 4 or 2x = -18

x = 2 or x = -9

Check the solutions.

Page 7: Solving Absolute Value Equations & Inequalities

Your Turn: Solve 2x - 5 = 9

Page 8: Solving Absolute Value Equations & Inequalities

How do you solve absolute value inequalities?

First, isolate the absolute value expression on the left side of the inequality

Then choose the form of your inequality

Page 9: Solving Absolute Value Equations & Inequalities

ax b c ax b c ax b c ax b c

Rewrite as

ax+b < c

And

ax+b > -c,

solve for x

Rewrite as

ax+b ≤ c

And

ax + b > -c,

solve for x

Rewrite as

ax + b > c

Or

ax + b < -c,

solve for x

Rewrite as

ax + b ≥ c

Or

ax + b ≤ -c,

solve for x

Page 10: Solving Absolute Value Equations & Inequalities

Solve Solve 4 2 22x 2 5 19x

Page 11: Solving Absolute Value Equations & Inequalities

Ex: Solve & graph.

• Becomes an “and” problem

2194 x

219421 x30412 x

2

153 x

-3 7 8

Page 12: Solving Absolute Value Equations & Inequalities

Solve & graph.

• Get absolute value by itself first.

• Becomes an “or” problem

11323 x

823 x

823or 823 xx63or 103 xx

2or 3

10 xx

-2 3 4

Page 13: Solving Absolute Value Equations & Inequalities

Your Turn: Solve & graph.

2 4 5 15x

Page 14: Solving Absolute Value Equations & Inequalities

Homework:Homework:


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