$\"\"$ $\"\"$

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The equation is $\"\"$

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Write two cases:

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Case-1: $\"\"$ .

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$\"\"$

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Case-2: $\"\"$

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$\"\"$

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$\"\"$

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Solve the equation for Case-1.

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Addition property of equality: if $\"\"$ , then $\"\"$ .

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$\"\"$

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$\"\"$ (Add 9 to both sides)

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$\"\"$ (Apply Additive inverse property: $\"\"$ )

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$\"\"$ (Apply Additive identity property: $\"\"$ )

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$\"\"$ (Add: $\"\"$ ) $\"\"$

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Check:

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To check the solution, substitute $\"\"$ in original equation.

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Subtract: $\"\"$ )

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The absolute value of 20 is 20.

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$\"\"$

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Compare the values the equation is true. $\"\"$ is a solution.

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$\"\"$

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Solve the equation for Case-2.

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$\"\"$

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Addition property of equality: if $\"\"$ , then $\"\"$ .

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$\"\"$ (Add 9 to both sides)

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$\"\"$ (Apply Additive inverse property: $\"\"$ )

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$\"\"$ (Apply Additive identity property: $\"\"$ )

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$\"\"$ (Add: $\"\"$ ) $\"\"$

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Check:

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To check the solution, substitute $\"\"$ in original equation.

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$\"\"$

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$\"\"$ (Add: $\"\"$ )

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$\"\"$ (The absolute value of $\"\"$ is 20)

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Compare the values the equation is true. $\"\"$ is a solution.

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$\"\"$

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The solutions are $\"\"$ . The solution set is $\"\"$ .