Solve the Fraction Equation: Finding X in 8/3 - 4/5x = -2/10x

Linear Equations with Fractional Coefficients

Find the value of the parameter X

8345x=210x \frac{8}{3}-\frac{4}{5}x=-\frac{2}{10}x

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve
00:03 We want to isolate the unknown X
00:08 Let's arrange the equation so that one side has only the unknown X
00:29 Let's simplify what we can
00:34 Let's factorize 10 into factors 2 and 5
00:41 Let's simplify what we can
00:52 Let's group terms
00:56 Let's isolate the unknown X and calculate
01:00 Let's multiply by the reciprocal fraction to eliminate the fraction
01:14 Make sure to multiply numerator by numerator and denominator by denominator
01:18 Let's simplify what we can
01:21 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Find the value of the parameter X

8345x=210x \frac{8}{3}-\frac{4}{5}x=-\frac{2}{10}x

2

Step-by-step solution

To solve the equation 8345x=210x \frac{8}{3} - \frac{4}{5}x = -\frac{2}{10}x , follow these steps:

  • Step 1: Identify the least common denominator (LCD) of the fractions involved. The denominators are 3, 5, and 10, so the LCD is 30.
  • Step 2: Multiply the entire equation by 30 to eliminate the fractions:
    30×(8345x)=30×(210x) 30 \times \left(\frac{8}{3} - \frac{4}{5}x\right) = 30 \times \left(-\frac{2}{10}x\right)
  • Step 3: Simplify each term:
    For 83\frac{8}{3}: 30×83=10×8=8030 \times \frac{8}{3} = 10 \times 8 = 80
    For 45x\frac{4}{5}x: 30×45x=6×4x=24x30 \times \frac{4}{5}x = 6 \times 4x = 24x
    For 210x-\frac{2}{10}x: 30×210x=3×2x=6x30 \times -\frac{2}{10}x = 3 \times -2x = -6x
  • Step 4: Rewrite the equation:
    8024x=6x 80 - 24x = -6x
  • Step 5: Combine like terms by moving terms containing x x to one side:
    Subtract 6x-6x from both sides:
    80=18x 80 = 18x
  • Step 6: Solve for x x by dividing both sides by 18:
    x=8018=409 x = \frac{80}{18} = \frac{40}{9} after simplification.

Therefore, the solution to the problem is x=409 x = \frac{40}{9} .

3

Final Answer

409 \frac{40}{9}

Key Points to Remember

Essential concepts to master this topic
  • LCD Method: Find common denominator to clear all fractions at once
  • Technique: Multiply entire equation by LCD 30: transforms 83 \frac{8}{3} to 80
  • Check: Substitute x=409 x = \frac{40}{9} back: both sides equal 83 \frac{8}{3}

Common Mistakes

Avoid these frequent errors
  • Forgetting to multiply every term by the LCD
    Don't multiply only the fraction terms by 30 and leave constants unchanged = unbalanced equation! This breaks the equality principle and leads to wrong solutions. Always multiply every single term on both sides by the LCD to maintain balance.

Practice Quiz

Test your knowledge with interactive questions

Solve for X:

\( x - 3 + 5 = 8 - 2 \)

FAQ

Everything you need to know about this question

Why multiply by 30 instead of just cross-multiplying?

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This equation has multiple terms with different denominators (3, 5, 10). Cross-multiplication only works for simple one fraction equals one fraction problems. The LCD method handles complex equations efficiently.

How do I find the LCD of 3, 5, and 10?

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List multiples of the largest denominator (10): 10, 20, 30, 40... The first number that's divisible by all denominators (3, 5, 10) is your LCD. So 303=10 \frac{30}{3} = 10 , 305=6 \frac{30}{5} = 6 , 3010=3 \frac{30}{10} = 3 .

Can I simplify fractions before solving?

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Yes! Notice 210x=15x -\frac{2}{10}x = -\frac{1}{5}x . Simplifying first makes the LCD easier to find. Your LCD becomes 15 instead of 30, making calculations simpler.

What if I get a different LCD?

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Any common multiple works, but the LCD gives the simplest numbers. Using 60 instead of 30 gives the same answer but with bigger numbers: 16048x=12x 160 - 48x = -12x still leads to x=409 x = \frac{40}{9} .

Why is my final answer a fraction?

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Many linear equations have fractional solutions! 409 \frac{40}{9} is already in simplest form since 40 and 9 share no common factors. Converting to mixed number: 449 4\frac{4}{9} .

How do I verify this answer is correct?

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Substitute x=409 x = \frac{40}{9} into the original equation:

  • Left side: 8345409=83329=89 \frac{8}{3} - \frac{4}{5} \cdot \frac{40}{9} = \frac{8}{3} - \frac{32}{9} = \frac{-8}{9}
  • Right side: 210409=89 -\frac{2}{10} \cdot \frac{40}{9} = -\frac{8}{9}

Both sides equal 89 -\frac{8}{9} , so our answer is correct!

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