Solve for X: 6.8 - 15x + 7x = 3.4 - 5.1 + 8x Linear Equation

Linear Equations with Decimal Coefficients

Solve for X:


6.815x+7x=3.45.1+8x 6.8-15x+7x=3.4-5.1+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
00:14 Arrange the equation so that only the unknown X is on one side
00:33 Collect terms
00:36 Isolate X
00:49 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:


6.815x+7x=3.45.1+8x 6.8-15x+7x=3.4-5.1+8x

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Step 1: Simplify both sides of the equation
  • Step 2: Move all x x terms to one side and constants to the other side
  • Step 3: Solve for x x

Now, let's work through each step:
Step 1: Simplify both sides of the equation:

On the left side, combine like terms:
6.815x+7x=6.88x 6.8 - 15x + 7x = 6.8 - 8x

On the right side, simplify:
3.45.1+8x=1.7+8x 3.4 - 5.1 + 8x = -1.7 + 8x

This gives us the simplified equation:
6.88x=1.7+8x 6.8 - 8x = -1.7 + 8x

Step 2: Move all x x terms to one side and constants to the other side.

Add 8x 8x to both sides to move x x terms to one side:
6.88x+8x=1.7+8x+8x 6.8 - 8x + 8x = -1.7 + 8x + 8x
This simplifies to:
6.8=1.7+16x 6.8 = -1.7 + 16x

Subsequently, add 1.7 1.7 to both sides to move constants to the opposite side:
6.8+1.7=16x 6.8 + 1.7 = 16x

This simplifies to:
8.5=16x 8.5 = 16x

Step 3: Solve for x x .

Divide both sides by 16 to isolate x x :
8.516=x \frac{8.5}{16} = x

This simplifies to:
x=0.53125 x = 0.53125

Rounding to two decimal places yields:
x=0.53 x = 0.53

Therefore, the solution to the problem is x=0.53 x = 0.53 .

3

Final Answer

0.53 0.53

Key Points to Remember

Essential concepts to master this topic
  • Rule: Combine like terms first before moving variables across equals
  • Technique: Move all x terms to one side: -8x + 8x = 16x total
  • Check: Substitute x = 0.53 back: 6.8 - 4.24 = -1.7 + 4.24 ✓

Common Mistakes

Avoid these frequent errors
  • Moving variables incorrectly across the equation
    Don't just move -8x to become +8x without adding to both sides = wrong equation! This violates the balance rule and gives incorrect answers. Always add or subtract the same amount from both sides to maintain equality.

Practice Quiz

Test your knowledge with interactive questions

Solve for X:

\( 6 - x = 10 - 2 \)

FAQ

Everything you need to know about this question

Why do I need to combine like terms first?

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Combining like terms simplifies the equation and makes it easier to solve! In this problem, 15x+7x=8x -15x + 7x = -8x reduces the complexity before moving variables.

What's the best way to keep track of positive and negative signs?

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Write each step clearly and use parentheses when needed. For example: 6.8+(8x)=1.7+8x 6.8 + (-8x) = -1.7 + 8x . This helps you see exactly what you're adding or subtracting.

How do I know which side to move the x terms to?

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It doesn't matter! You can move all x terms to either side. Choose the side that gives you a positive coefficient for x to avoid working with negatives.

Should I round my answer?

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Only if the problem asks you to! In this case, x=0.53125 x = 0.53125 rounds to 0.53, but always check what level of precision is required.

What if I get confused with all the decimal operations?

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Take it one step at a time! Write each calculation separately: 3.45.1=1.7 3.4 - 5.1 = -1.7 , then 6.8+1.7=8.5 6.8 + 1.7 = 8.5 . Breaking it down prevents errors.

How can I check if my final answer is correct?

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Substitute your answer back into the original equation. Replace every x with 0.53 and verify both sides equal the same value. If they do, you solved it correctly!

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