Class 9 · Mathematics · Ganita Manjari

3. The World of Numbers

Try question 1

Which of these numbers is irrational?

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Answer and explanation

Answer: A. √2

√2 cannot be written as p/q with integers p and q.

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Try question 2

The decimal expansion of an irrational number is

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Answer and explanation

Answer: C. non-terminating and non-recurring

Terminating or recurring decimals are rational; irrationals never end and never repeat.

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Try question 3

0.333… (3 repeating) written as a fraction is

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Answer and explanation

Answer: A. 1/3

Let x = 0.333…; then 10x − x = 3, so x = 3/9 = 1/3.

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