Question

2. Prove that 3 + 2V5 is irrational.
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Answer 1

Answer:

To prove: 3 + 2 root 5 is irrational

Let 3 + 2 root 5 is rational

therefore 3 + 2 root 5=a/b(where a and b are co prime integer )

root 5=a-3/2b

because a-3/2b is rational

therefore root 5 will also be rational

But we know that,

root 5 is irrational

that is our assumption is wrong that is 3+2 root 5 is irrational