Chapter 5: Problem 110
Perform the indicated operations. $$0 . \overline{5} \div 0 . \overline{2}-0.75$$
Short Answer
Expert verified
1.75
Step by step solution
01
Convert repeating decimals to fractions
First, convert the repeating decimals into fractions. \ \( 0. \overline{5} = \frac{5}{9} \) and \( 0. \overline{2} = \frac{2}{9} \)
02
Divide fractions
Divide the fractions \( \frac{5}{9} \div \frac{2}{9} \). To divide fractions, multiply by the reciprocal of the divisor: \( \frac{5}{9} \times \frac{9}{2} = \frac{5 \times 9}{9 \times 2} = \frac{45}{18} = \frac{5}{2} \).
03
Simplify the result
Simplify the fraction \( \frac{5}{2} \) to a decimal, which is \( 2.5 \).
04
Subtract 0.75
Subtract 0.75 from 2.5: \ \( 2.5 - 0.75 = 1.75 \)
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
repeating decimals to fractions
Repeating decimals can often seem tricky, but there's a systematic way to convert them into fractions. Let's take a repeating decimal like 0.\bar{5}.Here’s how you do it:
- First, you need to set the repeating decimal as a variable: Let’s call it \(x\). So, \(x = 0.\bar{5}\).
- Next, multiply both sides of the equation by a power of 10 such that the decimal part repeats after the decimal point. For \(0.\bar{5}\), you only need to multiply by 10: \(10x = 5.\bar{5}\).
- Subtract the original equation from this new one: \(10x - x = 5.\bar{5} - 0.\bar{5}\). This simplifies to \(9x = 5\).
- Finally, solve for \(x\) by dividing both sides by 9: \(x = \frac{5}{9}\).
dividing fractions
Dividing fractions may seem complex, but with the reciprocal method, it becomes easy. Let's consider you want to divide:\(\frac{5}{9} \text{ by } \frac{2}{9}\).Here’s how to do it:
- First, find the reciprocal of the divisor (the second fraction). The reciprocal of \(\frac{2}{9}\) is \(\frac{9}{2}\).
- Next, multiply the first fraction by this reciprocal: \(\frac{5}{9} \times \frac{9}{2}\).
- Multiply the numerators together and the denominators together: \(\frac{5 \times 9}{9 \times 2}\). This equals \(\frac{45}{18}\).
simplifying fractions
Simplifying fractions means reducing them to their lowest terms. In our previous example, we ended up with \(\frac{45}{18}\). Simplification works like this:
- Find the greatest common factor (GCF) of the numerator and the denominator. For 45 and 18, the GCF is 9.
- Divide both the numerator and the denominator by the GCF. Therefore, \( \frac{45}{18} \rightarrow \frac{45 \text{ ÷ 9}}{18 \text{ ÷ 9}} = \frac{5}{2}\).
decimal subtraction
Subtracting decimals is just like subtracting whole numbers, but it's important to line up the decimal points. Let’s subtract 0.75 from 2.5.Here’s a step-by-step guide:
- Write the numbers one under the other, ensuring the decimal points are aligned: \(2.500 \text{ and } 0.750\).
- If the length of the decimals differs, you can append zeros to the shorter decimal to make it easier: becomes \(2.500 - 0.750\).
- Subtract digit by digit starting from the rightmost side: \(0-0=0\),\(0-5=5\) (borrowing is necessary here),\(5-7=8\),\(and 2-0=2\).So, \(2.500 - 0.750 = 1.750\).