To solve the equation \( 9 (x + 1) = 3 (5x + 1) - 12 \), we will simplify both sides step by step.
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Expand both sides:
Left side: \[ 9(x + 1) = 9x + 9 \]
Right side: \[ 3(5x + 1) - 12 = 15x + 3 - 12 = 15x - 9 \]
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Now, we rewrite the equation with the simplified sides: \[ 9x + 9 = 15x - 9 \]
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Next, let's isolate \(x\) by moving all terms involving \(x\) to one side and constant terms to the other side: \[ 9 + 9 = 15x - 9x \] Simplifying this gives: \[ 18 = 6x \]
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Divide both sides by 6 to solve for \(x\): \[ x = 3 \]
Since we found a single solution \(x = 3\), the conclusion is that the equation has one solution.
The correct answer is:
D). The equation has one solution: x = 3.