To solve the equation \( 2(x−3)+21=−3 \), let's break it down step by step.
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Distribute to get: \[ 2(x - 3) + 21 = -3 \] Distributing \( 2 \) inside the parentheses: \[ 2x - 6 + 21 = -3 \]
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Combine like terms to get: \[ 2x + 15 = -3 \] Here, we combined \( -6 + 21 \) to get \( 15 \).
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Use the subtraction property of equality to get: \[ 2x = -3 - 15 \] Subtracting \( 15 \) from both sides.
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Use the addition property of equality to get: \[ 2x = -18 \]
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Use the division property of equality to get: \[ x = -9 \]
So the solution to the equation \( 2(x−3)+21=−3 \) is: \[ \boxed{-9} \]