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Question
Prove that of the numbers `3 sqrt(7)` is irrational:
Solution
Let `3 sqrt(7)` be rational.
`1/3 ×3 sqrt(7)= sqrt(7)` = rational [∵Product of two rational is rational]
This contradicts the fact that `sqrt(7)` is irrational.
The contradiction arises by assuming `3 sqrt(7)` is rational.
Hence, `3 sqrt(7)` is irrational.
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