/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 21 Express each of the numbers as t... [FREE SOLUTION] | 91Ó°ÊÓ

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Express each of the numbers as the ratio of two integers. $$0 . \overline{7}=0.7777 \ldots$$

Short Answer

Expert verified
The number \( 0.\overline{7} \) as a ratio of two integers is \( \frac{7}{9} \).

Step by step solution

01

Define the repeating decimal

Let \( x = 0.7777\ldots \). This is a repeating decimal where 7 repeats indefinitely.
02

Create an equation to eliminate the repeating part

Multiply \( x \) by 10 to shift the decimal point to the right: \( 10x = 7.7777\ldots \). The repeating part is unchanged.
03

Set up an equation to remove the decimal

Subtract the original equation from the new equation: \( 10x - x = 7.7777\ldots - 0.7777\ldots \). This simplifies to \( 9x = 7 \).
04

Solve for x

Divide both sides by 9 to express \( x \) as a ratio of two integers: \( x = \frac{7}{9} \).
05

Verify the solution

Convert \( \frac{7}{9} \) back to a decimal by dividing, confirming it equals \( 0.7777\ldots \).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Rational Numbers
Rational numbers are numbers that can be expressed as the quotient of two integers, where the numerator is an integer and the denominator is a non-zero integer. They are foundational to understanding mathematics as they include fractions and whole numbers.
  • Examples: Whole numbers (like 3 or -5) and fractions (like \( \frac{1}{2} \)).
  • Repeating decimals, such as 0.7777..., are also considered rational numbers because they can be converted into fractions.
The concept of rational numbers helps in comprehending how numbers can be broken down and expressed differently without changing their essence. The number 0.7777... is a perfect example, as it can be expressed as a fraction \( \frac{7}{9} \). By transforming repeating decimals into fractions, we gain a better understanding of their identity and how they fit into the broader category of rational numbers.
Fraction Conversion
Fraction conversion is essential for converting repeating decimals into their fractional equivalents. It involves a series of algebraic steps to adjust and simplify repeating patterns.
  • Identify the repeating decimal section, as seen with 0.7777..., where the digit 7 repeats endlessly.
  • Express this decimal as a variable, \( x = 0.7777\ldots \).
  • To clear the repeating portion, multiply by a power of ten to shift the decimal point; \( 10x = 7.7777\ldots \).
Once you've set up corresponding equations, subtract to eliminate the repeating segment and isolate \( x \). These steps make converting complex decimals into neat fractional representations manageable and systematic. The result is a rational expression, such as \( \frac{7}{9} \), demonstrating the number's rational nature.
Algebraic Manipulation
Algebraic manipulation is a powerful mathematical tool used to transform equations and expressions into usable forms. It involves methods such as rearranging equations, simplifying expressions, and using operations strategically.
  • In the case of repeating decimals, such as turning \( x = 0.7777\ldots \) into a fraction, algebraic manipulation is key.
  • Multiply the equation by 10 to align repeating parts: \( 10x = 7.7777\ldots \).
  • Subtract the original equation from this result to eliminate the repeating part: \( 10x - x = 7 \).
Solving for \( x \) afterward leads to \( x = \frac{7}{9} \). These techniques show how algebra can convert complex patterns into understandable, actionable results. With algebraic manipulation, even intricate decimal patterns reveal their true, simple fractional nature.

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Most popular questions from this chapter

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Taylor series for even functions and odd functions \(\quad\).Suppose that \(f(x)=\sum_{n=0}^{\infty} a_{n} x^{n}\) converges for all \(x\) in an open interval \((-R, R) .\) Show that a. If \(f\) is even, then \(a_{1}=a_{3}=a_{5}=\cdots=0,\) i.e., the Taylor series for \(f\) at \(x=0\) contains only even powers of \(x\) b. If \(f\) is odd, then \(a_{0}=a_{2}=a_{4}=\cdots=0,\) i.e., the Taylor series for \(f\) at \(x=0\) contains only odd powers of \(x\)

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