Q. \(-2x + 5(x – 4) – 3(2x – 3) = 10\).
Answer
\[
-2x + 5(x – 4) – 3(2x – 3) = 10
\]
\[
-2x + 5x – 20 – 6x + 9 = 10
\]
\[
-3x – 11 = 10
\]
\[
-3x = 21
\]
\[
x = -7
\]
Detailed Explanation
Step-by-step solution
-
Start with the given equation.
\[ -2x + 5(x – 4) – 3(2x – 3) = 10 \] -
Distribute the multiplication across each parenthesis. Multiply 5 by each term in (x − 4), and −3 by each term in (2x − 3).
\[ 5(x – 4) = 5x – 20 \]
\[ -3(2x – 3) = -6x + 9 \]
Substitute these into the equation:
\[ -2x + (5x – 20) + (-6x + 9) = 10 \] -
Remove the parentheses (they are not needed after distribution) and write all terms explicitly:
\[ -2x + 5x – 20 – 6x + 9 = 10 \] -
Combine like terms. First combine the x-terms:
\[ -2x + 5x – 6x = (-2 + 5 – 6)x = -3x \]
Then combine the constant terms:
\[ -20 + 9 = -11 \]
So the equation becomes:
\[ -3x – 11 = 10 \] -
Isolate the term with x by removing the constant on the left. Add 11 to both sides (this keeps the equality balanced):
\[ -3x – 11 + 11 = 10 + 11 \]
Simplify:
\[ -3x = 21 \] -
Solve for x by dividing both sides by −3 (again keeping the equality balanced):
\[ x = \frac{21}{-3} \]
Simplify the fraction:
\[ x = -7 \] -
Check the solution by substituting x = −7 back into the original equation. Compute each part:
\[ -2x = -2(-7) = 14 \]
\[ 5(x – 4) = 5(-7 – 4) = 5(-11) = -55 \]
\[ -3(2x – 3) = -3(2(-7) – 3) = -3(-14 – 3) = -3(-17) = 51 \]
Sum these results:
\[ 14 + (-55) + 51 = 14 – 55 + 51 = 10 \]
The right-hand side is 10, which matches the original right-hand side, so the solution is correct.
Solution: x = -7
See full solution
FAQs
How do I expand the parentheses in \( -2x + 5(x - 4) - 3(2x - 3) = 10 \)?
Apply the distributive property: \(5(x-4)=5x-20\) and \(-3(2x-3)=-6x+9\). So the left side becomes \(-2x + 5x - 20 - 6x + 9\).
How do I combine like terms after expanding?
Combine x-terms and constants: \(-2x+5x-6x = -3x\) and \(-20+9 = -11\). So the equation simplifies to \(-3x - 11 = 10\).
How do I isolate \(x\)?
Add 11 to both sides: \(-3x = 21\). Then divide by \(-3\): \(x = -7\).
What is the solution?
The unique solution is \(x = -7\).
How do I check the solution is correct?
Substitute \(x=-7\) into the original: \(-2(-7)+5(-7-4)-3(2(-7)-3)=14-55+51=10\). Since the left side equals 10, the solution is correct.
What common sign mistakes should I watch for?
What common sign mistakes should I watch for?
What is the distributive property used here?
The rule: \(a(b+c)=ab+ac\). It works with negatives: \(a(b-c)=ab-ac\). Use it to expand each parenthesis before combining like terms.
Could this equation have no solution or infinitely many solutions?
This linear equation has a nonzero coefficient for \(x\) (\(-3\)), so it has a unique solution. No/infinite solutions occur only if \(x\) terms cancel and constants conflict or match.
Step-by-step solution for equation.
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