Question

prove that 2 root 5 is irrational​

Answer 1

Let us assume that 2+root5 is rational

SO,

2+root5 = a/b

Root5 = a/b-2 =a-2b/b

But we know that root5 is irrational

So,

Our assumption was wrong

Therefore, 2+root5 is irrational

Hence proved.