Math Problem Statement
Show that the following number is rational by writing it as a ratio of two integers.
0.71717171…
Solution
The number is a repeating decimal, and we can express it as a fraction, proving that it is rational. Here's how we do it step by step:
Let
Step 1: Multiply both sides by 100
Since the decimal repeats every two digits, we multiply by to shift the decimal point two places to the right:
Step 2: Subtract the original equation from this new equation
Now subtract from :
This simplifies to:
Step 3: Solve for
Now, solve for by dividing both sides by 99:
Thus, is equal to , which is a ratio of two integers, so it is a rational number.
Would you like further details or clarifications?
Here are 5 related questions for further exploration:
- How can we convert other repeating decimals into fractions?
- What is the difference between rational and irrational numbers?
- Can a repeating decimal ever be an irrational number?
- How would you convert into a fraction?
- What properties do rational numbers have in relation to repeating decimals?
Tip: A decimal that repeats after a fixed number of digits is always a rational number.
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Math Problem Analysis
Mathematical Concepts
Algebra
Repeating Decimals
Rational Numbers
Formulas
x = repeating decimal, 100x = shifted decimal, solve for x using subtraction
Theorems
Rational Number Theorem: A decimal that repeats is always rational
Suitable Grade Level
Grades 8-10