Chapter 19: Problem 20
Find the fractions equal to the given decimals. $$0.070707 \ldots$$
Short Answer
Expert verified
0.070707... equals the fraction \( \frac{7}{99} \).
Step by step solution
01
Identify the Repeating Decimal
The decimal is given as 0.070707... The repeating part of the decimal is 07. This means the decimal 0.070707... is a repeating decimal with block 07.
02
Set Up the Equation for the Repeating Decimal
Let the repeating decimal be represented as a variable, say \( x = 0.070707\ldots \). The repeating part has two digits (07), hence we will multiply \( x \) by 100, because 10 squared is 100.
03
Form the Equation by Subtracting
Calculate \( 100x = 7.070707\ldots \). Now subtract the original \( x = 0.070707\ldots \) from this equation to eliminate the repeating part: \( 100x - x = 7.070707\ldots - 0.070707\ldots \).
04
Simplify the Equation
The subtraction yields: \( 99x = 7 \).
05
Solve for x
Divide both sides of \( 99x = 7 \) by 99 to isolate \( x \): \( x = \frac{7}{99} \).
06
Conclusion
The decimal 0.070707... can be expressed as the fraction \( \frac{7}{99} \). This fraction is already in simplest form as 7 is a prime number and does not divide 99 evenly.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Fraction Conversion
When faced with a repeating decimal, the goal is to convert it into a simple fraction. This allows for a clearer representation of the number. It might seem a bit tricky at first, but it's quite systematic once you understand the steps.
- Start by identifying the repeating sequence. For example, in the decimal 0.070707..., the repeating part is '07'.
- Next, assign a variable like \( x \) to represent the decimal. Here, \( x = 0.070707... \).
- Decide how many digits are in the repeating block. If there are two digits, you will multiply \( x \) by 100 (because \( 10^2 = 100 \)), effectively shifting the decimal to remove the repeats temporarily.
- Use basic algebra to set up an equation where the repeating parts cancel out, allowing you to solve for \( x \).
Decimal Representation
Decimals have two major types: terminating and repeating. A repeating decimal shows a sequence that endlessly recurs, such as 0.070707..., where '07' is the repeating part.
- Repeating decimals can often be identified by an overline, such as \( 0.07\overline{07} \) or by simply analyzing the sequence presented.
- The block of repeating numbers sets the stage for how we shift and manipulate the decimal during conversion to a fraction.
Simplifying Fractions
Once you've converted a repeating decimal into a fraction, you might need to simplify it. Simplifying is the process of reducing the fraction to its smallest numerator and denominator without changing its value.
- For example, after solving the equation from a repeating decimal, you may find \( \frac{7}{99} \). To check if it's in simplest form, find the greatest common divisor (GCD) of the numerator and the denominator.
- If the GCD is 1 (meaning the numbers are coprime), the fraction is already simplified.
- If not, divide both the numerator and the denominator by their GCD.