Q40 / 90 · JEE Main 2023 (06 Apr Shift 2) · Mathematics

Let the sets A and B denote the domain and range respectively of the function fx=1x-x, where x denotes the smallest integer greater than or equal to x. Then among the statements

S1: A∩B=1, ∞-ℕ and

S2: A∪B=1, ∞

  • A
    Only (S2) is true
  • B
    Only (S1) is true
  • Correct answer
    C
    Neither S1 nor S2 is true
  • D
    Both S1 and S2 are true

Solution

Given,

fx=1x-x

We know that, x=x+x where x is fractional part of x whose value is 0<x<1,

So, x-x=-x

Now putting the value in given function we get,

fx=1x-x

⇒fx=1-x

Now we know that 1gx is defined when gx>0, but -x∈-1,0

Hence, -x is not defined

Hence, Domain and Range will be=ϕ 

Hence, the correct answer is option: 'C'.

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