Question

prove that 2-3root5 is an irrational no.

Answer 1

2-3 root 5=(a÷b)
-3root5=(a÷b)-2
3root5 =2-(a÷b)
3root5 =(2b-a)÷b
a,b and 5 all are integers

(2b-a)÷b is rational
3root5 will be also rational
but this contradicts the fact that 3root5 is irrational number.

hence,2-3root5 is a irrational number