Solve the Equation with Constants 74.1 and 18.8 to Find X

Linear Equations with Decimal Coefficients

Solve for X:


74.13.5x+10.2x=13.2x16.718.8 74.1-3.5x+10.2x=13.2x-16.7-18.8

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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
00:21 Arrange the equation so that one side has only the unknown X
00:50 Collect terms
01:00 Isolate X
01:13 And 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:


74.13.5x+10.2x=13.2x16.718.8 74.1-3.5x+10.2x=13.2x-16.7-18.8

2

Step-by-step solution

Let's solve the problem step-by-step:

  • Step 1: Combine like terms on both sides of the equation.

The given equation is:

74.13.5x+10.2x=13.2x16.718.8 74.1 - 3.5x + 10.2x = 13.2x - 16.7 - 18.8

First, combine like terms on the left-hand side (LHS):

3.5x+10.2x=6.7x -3.5x + 10.2x = 6.7x
Thus, the LHS becomes 74.1+6.7x 74.1 + 6.7x .

Combine constant terms on the right-hand side (RHS):

16.718.8=35.5 -16.7 - 18.8 = -35.5

Thus, the RHS becomes 13.2x35.5 13.2x - 35.5 .

  • Step 2: Move all terms containing x x to one side of the equation and constants to the other side.

Rearrange the equation:

74.1+6.7x=13.2x35.5 74.1 + 6.7x = 13.2x - 35.5

Let's bring all terms with x x to one side by subtracting 6.7x 6.7x from both sides:

74.1=13.2x6.7x35.5 74.1 = 13.2x - 6.7x - 35.5

This simplifies to:

74.1=6.5x35.5 74.1 = 6.5x - 35.5

  • Step 3: Solve for x x .

Add 35.5 35.5 to both sides to isolate terms with x x :

74.1+35.5=6.5x 74.1 + 35.5 = 6.5x

109.6=6.5x 109.6 = 6.5x

Finally, divide both sides by 6.5 6.5 :

x=109.66.5 x = \frac{109.6}{6.5}

Calculate the division:

x=16.86 x = 16.86

Therefore, the solution to the problem is x=16.86 x = 16.86 .

3

Final Answer

16.86 16.86

Key Points to Remember

Essential concepts to master this topic
  • Combining Like Terms: Add coefficients of x terms: -3.5x + 10.2x = 6.7x
  • Technique: Collect constants: -16.7 - 18.8 = -35.5 on right side
  • Check: Substitute x = 16.86: 74.1 + 6.7(16.86) = 13.2(16.86) - 35.5 ✓

Common Mistakes

Avoid these frequent errors
  • Incorrectly combining like terms with different signs
    Don't combine -3.5x + 10.2x as 13.7x = wrong coefficient! This ignores the negative sign and leads to completely wrong answers. Always pay attention to signs: -3.5 + 10.2 = 6.7, so -3.5x + 10.2x = 6.7x.

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 numbers when combining like terms?

+

Treat it like regular addition and subtraction! For -3.5x + 10.2x, think: -3.5 + 10.2 = 6.7, so the result is 6.7x. The key is keeping track of the signs.

Why do I need to combine constants separately from x terms?

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Because x terms and constant terms are different types! You can only combine terms that are exactly alike. Think of it like combining apples with apples, not apples with oranges.

What if I get a decimal answer - is that normal?

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Absolutely! Decimal answers are very common with decimal coefficients. x = 16.86 is a perfectly valid solution. Just make sure to check your arithmetic carefully.

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. In this problem, we moved them to the right side to get 6.5x, but moving them left would work too.

Should I convert decimals to fractions to solve this?

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Not necessary! Working with decimals directly is often easier and faster. Just be careful with your arithmetic and use a calculator if needed to avoid mistakes.

How can I check if my combining of constants is correct?

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Double-check: -16.7 - 18.8 = -35.5. Remember that subtracting a positive number is the same as adding a negative: -16.7 + (-18.8) = -35.5.

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