Solve for X in the Equation: 2/8x - 3 = 7

Linear Equations with Fractional Coefficients

Solve for X:

28x3=7 \frac{2}{8}x-3=7

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:07 Let's solve this problem.
00:10 First, we need to find X by itself.
00:14 We do this by rearranging the equation, so X is on one side.
00:23 Next, we simplify as much as possible.
00:35 Then, we multiply by the denominator to get rid of the fraction.
00:50 Simplify again where you can.
00:56 Keep isolating X and plug in the values to calculate.
01:06 And that's the solution to our problem!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve for X:

28x3=7 \frac{2}{8}x-3=7

2

Step-by-step solution

To solve the equation 28x3=7 \frac{2}{8}x - 3 = 7 , we'll follow these steps:

  • Step 1: Simplify the fraction. The coefficient 28 \frac{2}{8} simplifies to 14 \frac{1}{4} .
  • Step 2: Eliminate the constant term by adding 3 to both sides of the equation.
  • Step 3: Solve for x x by removing the coefficient of x x using division.

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

Step 1: Simplify the equation:
The equation 28x3=7 \frac{2}{8}x - 3 = 7 simplifies to 14x3=7 \frac{1}{4}x - 3 = 7 .

Step 2: Eliminate the constant term:
Add 3 to both sides to isolate the term involving x x :

14x3+3=7+3\frac{1}{4}x - 3 + 3 = 7 + 3

This simplifies to:

14x=10\frac{1}{4}x = 10

Step 3: Solve for x x :
Multiply both sides by the reciprocal of 14 \frac{1}{4} to solve for x x :

414x=4104 \cdot \frac{1}{4}x = 4 \cdot 10

This simplifies to:

x=40x = 40

Therefore, the solution to the equation is x=40 x = 40 .

3

Final Answer

40

Key Points to Remember

Essential concepts to master this topic
  • Simplify First: Reduce fractions like 2/8 to 1/4 before solving
  • Technique: Add 3 to both sides: 1/4x = 10
  • Check: Substitute x = 40: 1/4(40) - 3 = 10 - 3 = 7 ✓

Common Mistakes

Avoid these frequent errors
  • Not simplifying the fraction coefficient first
    Don't work with 2/8x when you can simplify to 1/4x = harder calculations and more chance for errors! This makes multiplying by the reciprocal much more complex. Always simplify fractions before solving the equation.

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 should I simplify 2/8 to 1/4 first?

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Simplifying makes the math much easier! Working with 1/4 instead of 2/8 means multiplying by 4 instead of 8/2, which reduces calculation errors and saves time.

Can I multiply both sides by 8 instead of 4?

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Yes, but it's unnecessarily complicated! You'd get 2x - 24 = 56, then 2x = 80, so x = 40. The answer is the same, but with bigger numbers that are harder to work with.

What if I forget to add 3 to both sides?

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You'll get the wrong answer! If you divide 14x3 \frac{1}{4}x - 3 by 14 \frac{1}{4} , you get a messy expression. Always isolate the x-term first by adding or subtracting constants.

How do I multiply by the reciprocal of 1/4?

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The reciprocal of 14 \frac{1}{4} is 41=4 \frac{4}{1} = 4 . So multiply both sides by 4: 4×14x=4×10 4 \times \frac{1}{4}x = 4 \times 10 , which gives you x=40 x = 40 .

What's the fastest way to check my answer?

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Substitute x = 40 back into the original equation: 28(40)3=8083=103=7 \frac{2}{8}(40) - 3 = \frac{80}{8} - 3 = 10 - 3 = 7

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