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A Coefficient Inside

Part of the Inequalities & Absolute Value section of Coddy's Algebra journey. Lesson 42 of 61.

In ∣2x−1∣=7\left|2x-1\right| = 7, the expression inside the bars is 2x−12x-1. Split into two cases first. Each case is then a two-step equation: add 1 to both sides, then divide both sides by 2.

2x−1=72x-1 = 7

2x=82x = 8

x=4x = 4

or

2x−1=−72x-1 = -7

2x=−62x = -6

x=−3x = -3

The two cases give x=4x = 4 or x=−3x = -3. Check each answer in the original equation. For x=−3x = -3, the inside is 2⋅(−3)−1=−72\cdot \left(-3\right)-1 = -7, and ∣−7∣=7\left|-7\right| = 7, so the answer checks. Keep both answers.

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Challenge

Medium

Solve the equation ∣2x+3∣=9\left|2x+3\right| = 9 for xx.

Try it yourself

∣2x+3∣=9\left|2x+3\right| = 9

Get xx alone

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