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Prove that (√3 + √5) is irrational. |
Answer» Let us assume that √3 + √5 is rational On squaring, we get (√3 + √5)2 is rational 3 + 2√3 x √5 + 5 is rational 8 + 2√15 is rational Subtract 8 from above result, considering 8 is a rational number. As we know, Difference of two rational numbers is a rational. 8 + 2√15 – 8 is rational 2√15 is rational Which is only possible if 2 is rational and √15 is rational. The fact is √15 is not a rational number. Our assumption is wrong, and (√3 + √5) is irrational. |
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