Solve for X: -x + 3(x-4) = 5 - 1/2x Linear Equation

Linear Equations with Mixed Fraction Terms

Solve for x:

x+3(x4)=512x -x+3(x-4)=5-\frac{1}{2}x

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find X
00:04 Open brackets properly, multiply by each factor
00:16 Collect like terms
00:26 Arrange the equation so that X is isolated on one side
00:46 Collect like terms
00:53 Convert from mixed number to fraction
00:57 Multiply by the reciprocal to isolate X
01:13 This is the solution to the problem

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve for x:

x+3(x4)=512x -x+3(x-4)=5-\frac{1}{2}x

2

Step-by-step solution

To solve the equation x+3(x4)=512x-x + 3(x-4) = 5 - \frac{1}{2}x, follow these steps:

  • **Step 1**: Distribute the 33 on the left side:
    x+3x12=512x-x + 3x - 12 = 5 - \frac{1}{2}x.
  • **Step 2**: Combine like terms on the left:
    (2x12)=512x(2x - 12) = 5 - \frac{1}{2}x.
  • **Step 3**: Add 12x\frac{1}{2}x to both sides to get only the variable terms on one side:
    2x+12x12=52x + \frac{1}{2}x - 12 = 5.
  • **Step 4**: Simplify by combining the xx terms:
    52x12=5\frac{5}{2}x - 12 = 5.
  • **Step 5**: Add 12 to both sides to isolate terms with xx:
    52x=17\frac{5}{2}x = 17.
  • **Step 6**: Multiply both sides by 25\frac{2}{5} to solve for xx:
    x=17×25=345x = 17 \times \frac{2}{5} = \frac{34}{5}.

Therefore, the solution to the problem is x=345x = \frac{34}{5}.

3

Final Answer

345 \frac{34}{5}

Key Points to Remember

Essential concepts to master this topic
  • Distribution: Apply distributive property before combining like terms
  • Technique: Convert 2x+12x 2x + \frac{1}{2}x to 52x \frac{5}{2}x by finding common denominator
  • Check: Substitute x=345 x = \frac{34}{5} back: both sides equal 5 ✓

Common Mistakes

Avoid these frequent errors
  • Forgetting to distribute the 3 to both terms inside parentheses
    Don't just multiply 3(x) and ignore the -4 = missing -12 term! This creates an incomplete equation and wrong final answer. Always distribute to every term: 3(x-4) = 3x - 12.

Practice Quiz

Test your knowledge with interactive questions

\( x+x=8 \)

FAQ

Everything you need to know about this question

Why do I need to distribute first instead of moving terms around?

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You must distribute first because parentheses create a single unit. Moving terms before distributing changes the equation's meaning and leads to wrong answers!

How do I add 2x and 1/2x together?

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Convert to the same denominator: 2x=42x 2x = \frac{4}{2}x , so 42x+12x=52x \frac{4}{2}x + \frac{1}{2}x = \frac{5}{2}x . Always find a common denominator when adding fractions!

Can I multiply everything by 2 to clear the fraction?

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Yes! Multiplying both sides by 2 eliminates 12x \frac{1}{2}x and makes calculations easier. Just remember to multiply every single term on both sides.

Why is my answer a fraction instead of a whole number?

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Not all equations have whole number solutions! x=345 x = \frac{34}{5} is perfectly correct. You can convert to decimal (6.8) or mixed number (6⅘) if needed.

How do I check if 34/5 is really correct?

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Substitute back into the original equation: 345+3(3454)=512345 -\frac{34}{5} + 3(\frac{34}{5} - 4) = 5 - \frac{1}{2} \cdot \frac{34}{5} . Both sides should equal 5 when simplified!

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