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Isolate, Then Split

Part of the Inequalities & Absolute Value section of Coddy's Algebra journey. Lesson 49 of 61.

As with equations, the absolute value must be alone before you split. In 2∣x∣+1>72\left|x\right|+1 > 7, subtract 1 from both sides, divide both sides by 2, and only then split.

2∣x∣>62\left|x\right| > 6

∣x∣>3\left|x\right| > 3

Now split into two cases: x>3x > 3 or x<−3x < -3.

The same goes for a "less than". In ∣x−3∣−1≤1\left|x-3\right|-1 \le 1, add 1 to both sides first to get ∣x−3∣≤2\left|x-3\right| \le 2. Then write the chain −2≤x−3≤2-2 \le x-3 \le 2 and add 3 to all three parts, so 1≤x≤51 \le x \le 5. The order is: isolate the absolute value, decide whether it is a "less than" (a chain) or a "greater than" (an "or"), split, then solve.

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Challenge

Medium

Solve ∣x+1∣−2≤2\left|x+1\right|-2 \le 2.

Try it yourself

∣x+1∣−2≤2\left|x+1\right|-2 \le 2

Get xx alone on one side

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