Q. Solve the Equation: \( -3(x – 14) + 9x = 6x + 42 \)
Answer
- Expand the left side.
Distribute the -3.
\[ -3x + 42 + 9x = 6x + 42 \]
- Combine like terms.
\[ 6x + 42 = 6x + 42 \]
- Isolate x.
Subtract 6x from both sides.
\[ 42 = 42 \]
- Conclusion.
This is an identity. Every real number satisfies the equation.
\[ x \in \mathbb{R} \]
Detailed Explanation
Problem: Solve the equation \( -3(x – 14) + 9x = 6x + 42 \).
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Distribute (use the distributive property):
Multiply \(-3\) by each term inside the parentheses \( (x – 14) \).
Computation: \( -3(x – 14) = -3\cdot x + (-3)\cdot(-14) = -3x + 42 \).
After distribution the equation becomes \( -3x + 42 + 9x = 6x + 42 \).
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Combine like terms on the left-hand side:
Combine the \(x\)-terms \(-3x\) and \(9x\): \( -3x + 9x = 6x \).
So the left-hand side simplifies to \(6x + 42\), giving the equation \( 6x + 42 = 6x + 42 \).
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Compare both sides and attempt to isolate the variable:
Subtract \(6x\) from both sides to try to isolate \(x\):
Computation: \( 6x + 42 – 6x = 6x + 42 – 6x \) which yields \( 42 = 42 \).
Alternatively, subtract \(42\) from both sides to obtain \( 6x = 6x \) and then \( 0 = 0 \) after subtracting \(6x\); both lead to a true identity.
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Conclusion about solutions:
Because the equation simplifies to a true statement that does not involve \(x\) (for example \(42 = 42\) or \(0 = 0\)), the original equation is an identity: it is true for every real number \(x\).
Therefore the solution set is all real numbers, written as \( \mathbb{R} \) or \( (-\infty, \infty) \).
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Quick verification (optional):
Pick any value of \(x\), for example \(x = 0\):
Left side: \( -3(0 – 14) + 9\cdot 0 = -3(-14) + 0 = 42.\)
Right side: \( 6\cdot 0 + 42 = 42.\)
Both sides match, consistent with the conclusion that every real \(x\) satisfies the equation.
Final answer: All real numbers (solution set \( \mathbb{R} \) or \( (-\infty, \infty) \)).
Frequently Asked Questions
What is the solution to -3(x - 14) + 9x = 6x + 42?
How do I distribute the -3 correctly?
Why do I combine 9x and -3x?
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