Question

Please solve it its fro NTSE 2016-17​

Answer 1

Let the number be x with reciprocal of 1/x such that

x+1/x=4

We have to find the value of x-1/x

So, [x+1/x]^2=(4)^2

X^2 + 1/x^2 +2 =16

X^2 + 1/x^2 + 2 - 4=16 - 4

X^2 + 1/x^2 - 2=12

[X-1/x]^2=12

x - 1/x =sqrt(12)=2sqrt(3)

So, option 4 is correct one.