Solve

Step

| 4x + 1 | < 9  

-9 < 4x + 1 < 9

-9 – 1 < 4x + 1 –  1 < 9 – 1

-10 < 4x < 8

-10/4 < x < 8/4

-5/2 < x < 2

(-5/2, 2)

Use this technique when 
   |x| < a   
-a < x < a 

Subtract 1 from each part

Divide each part by 4

Reduce fractions 
        when possible

Inequality Notation

Interval Notation

Graph

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Click Link for Inequality Grapher.