Rajasthan BoardEnglish MediumSTD 9MATHSNumber systems1 Mark
Question
If n is a natural number, then $\sqrt{\text{n}}$ is:
✓
Answer
sometimes a natural number and sometimes an irrational number. Solution:
Is incorrect, because $\sqrt{\text{n}}$ can not be always a natural number i.e. if $\text{n}=2, \ \sqrt{\text{n}}=\sqrt{2}$ (not a natural no.)
Is incorrect, similiarly, if n = 2, 5, …. Or any odd no. or not perfect square, $\sqrt{\text{n}}=\sqrt{2},\sqrt{5},\sqrt{7}$ are Non-terminating and non-repeating, So irrational in nature, So, not always a rational number.
Is also incorrect, $\sqrt{\text{n}}$ can aslo be rational or say a natural number. If n = 4, 9, 16... or any perfect square number then $\sqrt{\text{n}}=2,3,4...$ natural numbers.
Is fully correct because if n is any odd number or non-perfect square number then $\sqrt{\text{n}}$ would be irrational, but if n is a perfect square number $\sqrt{\text{n}}$ then will be a natural number. If n = 2, 3, 5, 8 ... $\sqrt{\text{n}}=\sqrt{2},\sqrt{3},\sqrt{8}...$ (irrational) If n = 4, 9, 16 ... = 2, 3, 4 ... (Natural number) So, correct option is (d).
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