$\"\"$

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

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The expression is $\"\"$ .

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Apply subtraction property of equality: Subtract 72 from each side.

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$\"\"$

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

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$\"\"$ (Apply Additive identity property: a + 0 = a) $\"\"$

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Apply division property of equality: Divide each side by 6.

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$\"\"$

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$\"\"$ (Cancel common terms)

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$\"\"$ (Divide: $\"\"$ )

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$\"\"$ (Take square root each side) $\"\"$

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$\"\"$

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Rewrite the expression using product property of square roots;

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For nonnegative real numbers a and b, $\"\"$ .

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

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Rewrite the ( $\"\"$ ) using imaginary unit; that is $\"\"$ where $\"\"$ .

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$\"\"$

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Find the square root: $\"\"$ .

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$\"\"$

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$\"\"$ (Multiply: $\"\"$ ) $\"\"$

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The value of $\"\"$ .