Solve Linear Equation: 80-3.6x+7.4x=49+51-5.8x with Decimal Coefficients

Linear Equations with Decimal Simplification

Solve for X:

803.6x+7.4x=49+515.8x 80-3.6x+\text{7}.4x=49+51-5.8x

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find X
00:05 Collect terms
00:17 Arrange the equation so that one side has only the unknown X
00:39 Collect terms
00:45 Isolate X
00:56 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

Solve for X:

803.6x+7.4x=49+515.8x 80-3.6x+\text{7}.4x=49+51-5.8x

2

Step-by-step solution

To solve this linear equation, we will carefully combine like terms and isolate the variable x x . Here are the steps:

  • Step 1: Simplify both sides of the equation by combining like terms.
    On the left side: 803.6x+7.4x=80+3.8x 80 - 3.6x + 7.4x = 80 + 3.8x (combining 3.6x -3.6x and 7.4x 7.4x ).
  • Step 2: Simplify the right side of the equation:
    49+515.8x=1005.8x 49 + 51 - 5.8x = 100 - 5.8x . (Notice we combine 49 49 and 51 51 to get 100 100 ).
  • Step 3: Write the simplified equation:
    80+3.8x=1005.8x 80 + 3.8x = 100 - 5.8x .
  • Step 4: Move all x x -terms to one side and constant terms to the other side by adding 5.8x 5.8x to both sides and subtracting 80 80 from both sides:
    3.8x+5.8x=10080 3.8x + 5.8x = 100 - 80
  • Step 5: Combine the x x -terms and simplify constants:
    9.6x=20 9.6x = 20 .
  • Step 6: Solve for x x by dividing both sides by 9.6 9.6 :
    x=209.6 x = \frac{20}{9.6} .
  • Step 7: Compute the division:
    x2.08 x \approx 2.08 .

Upon looking at the choices provided, the correct choice is 2.08 \boxed{2.08} , which is choice 2 2 .

Therefore, the solution to the problem is x=2.08 x = 2.08 .

3

Final Answer

2.08 2.08

Key Points to Remember

Essential concepts to master this topic
  • Combine Like Terms: Group x-terms and constants separately before isolating variable
  • Technique: -3.6x + 7.4x = 3.8x by adding coefficients: 7.4 - 3.6
  • Check: Substitute x = 2.08 back: 80 + 3.8(2.08) should equal 100 - 5.8(2.08) ✓

Common Mistakes

Avoid these frequent errors
  • Incorrectly combining decimal coefficients
    Don't subtract -3.6x + 7.4x = 10.1x by adding the absolute values! This ignores the negative sign and gives x = 0.95 instead of 2.08. Always pay attention to signs when combining: -3.6 + 7.4 = 3.8.

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

How do I handle negative coefficients with decimals?

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Treat them just like regular numbers! For 3.6x+7.4x -3.6x + 7.4x , think of it as -3.6 + 7.4 = 3.8, so you get 3.8x 3.8x .

Why do we get a decimal answer instead of a whole number?

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When equations have decimal coefficients, the solution is often a decimal too! That's completely normal - not all equations have nice whole number answers.

Should I round my final answer?

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Only if the problem asks you to! In this case, 209.6=2.083 \frac{20}{9.6} = 2.08\overline{3} , but since 2.08 is one of the answer choices, that's the expected precision.

How can I check if 2.08 is really correct?

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Substitute back into the original equation: 803.6(2.08)+7.4(2.08) 80 - 3.6(2.08) + 7.4(2.08) should equal 1005.8(2.08) 100 - 5.8(2.08) . Both sides give approximately 87.9!

What if I make an arithmetic error with the decimals?

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Double-check each step! Write out every calculation clearly: 49 + 51 = 100, then -3.6 + 7.4 = 3.8, then 3.8 + 5.8 = 9.6. Take your time with decimal arithmetic.

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