Question 1. Classify the Following Numbers As Rational orIrratio Exercise 1.5 Chapter 1 Number System Maths Class 9

Question 1. Classify the following numbers as rational or irrational:

Solution: (i)2 - √5

Here 2 is a rational number and √5 is a irrational number
And difference of rational and irrational is always a irrational number
So that 2 - √5 is a irrational number

(ii) (3 +  √23) - √23

Solve the bracket we get

3 +  √23 - √23  = 3

and 3 is a rational number so that (3 +  √23) - √23 is a rational number

(iii)   and 2/7 can be written in form of p/q so it a rational number

(iv) 1/ √2  is an irrational number because 1 is rational and √2 is irrational and product or division of rational with irrational is always irrational

(v) 2pi   it is an irrational here 2 is rational and pi is a irrational number and product or division of rational with irrational is always irrational