Math Problem Statement

You can write 0.7 (repeating) as a fraction using equations. Simplify the left side of the equation 10x - x = 7.7 - 0.7.

Solution

In this problem, we need to convert 0.70.\overline{7} (a repeating decimal) into a fraction by solving an equation.

Step-by-Step Solution:

  1. Let x=0.7x = 0.\overline{7}. This repeating decimal is the same as writing 0.77777...0.77777... with 77 repeating indefinitely.

  2. Multiply both sides of the equation x=0.7x = 0.\overline{7} by 10 to shift the decimal point: 10x=7.710x = 7.\overline{7}

  3. Now we have two equations: x=0.7x = 0.\overline{7} 10x=7.710x = 7.\overline{7}

  4. Subtract the first equation from the second: 10xx=7.70.710x - x = 7.\overline{7} - 0.\overline{7} 9x=79x = 7

  5. Divide both sides by 9 to isolate xx: x=79x = \frac{7}{9}

Therefore, 0.70.\overline{7} can be written as the fraction 79\frac{7}{9}.

Would you like further details on any of the steps or have any questions?


Additional Questions for Further Exploration

  1. How can repeating decimals other than 0.70.\overline{7} be converted to fractions?
  2. What is the difference in approach for converting non-repeating decimals to fractions?
  3. Can you use this method to convert 0.30.\overline{3} to a fraction?
  4. Why does subtracting the equations help in isolating xx?
  5. How does this approach apply to repeating decimals with more than one digit, like 0.230.\overline{23}?

Tip

When converting a repeating decimal to a fraction, multiply by a power of 10 that matches the number of repeating digits. This helps align the decimal parts for subtraction.

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Math Problem Analysis

Mathematical Concepts

Algebra
Repeating Decimals
Fraction Conversion

Formulas

10x - x = 7.7 - 0.7

Theorems

Properties of Equations

Suitable Grade Level

Grades 7-9