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Is the following number rational or irrational?

0. bar(7)
Choose 1 answer:
(A) Rational
(B) Irrational

Is the following number rational or irrational?\newline0.70.\overline{7}\newlineChoose 11 answer:\newline(A) Rational\newline(B) Irrational

Full solution

Q. Is the following number rational or irrational?\newline0.70.\overline{7}\newlineChoose 11 answer:\newline(A) Rational\newline(B) Irrational
  1. Evaluate the meaning: Evaluate the meaning of 0.70.\overline{7}.\newline0.70.\overline{7} means 0.7777770.777777\ldots, where the digit 77 repeats indefinitely.
  2. Set up an equation: Set up an equation to represent 0.70.\overline{7}.\newlineLet x=0.7x = 0.\overline{7}.
  3. Multiply both sides: Multiply both sides of the equation by 1010 to shift the decimal point one place to the right.\newline10x=7.7.10x = 7.\overline{7}.
  4. Subtract the original equation: Subtract the original equation (x=0.7)(x = 0.\overline{7}) from the new equation (10x=7.7)(10x = 7.\overline{7}) to get rid of the repeating decimals.\newline10xx=7.70.710x - x = 7.\overline{7} - 0.\overline{7}.
  5. Perform the subtraction: Perform the subtraction to find the value of 9x9x.9x=79x = 7
  6. Divide both sides: Divide both sides by 99 to solve for xx.\newlinex=79x = \frac{7}{9}
  7. Identify whether: Identify whether 79\frac{7}{9} is a rational or irrational number.\newline79\frac{7}{9} is a fraction which represents a ratio of two integers, therefore it is a rational number.
  8. Conclude that: Conclude that 0.70.\overline{7} is a rational number because it can be expressed as the fraction 79\frac{7}{9}.

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