Q22 / 54 · JEE Advanced 2019 (Paper 2) · Mathematics

Let F:R→R be a function. We say that f has:
 PROPERTY 1  if limh→0⁡fh-f0h exists and is finite, and 
PROPERTY 2  if limh→0⁡fh-f0h2 exists and is finite.
Then which of the following options is/are correct?

  • A
    fx=xx has PROPERTY 2
  • Correct answer
    B
    fx=x2/3 has PROPERTY 1
  • C
    fx=sin⁡x has PROPERTY 2
  • Correct answer
    D
    fx=x has PROPERTY 1

Solution

A fx=x
limh→0⁡h-0h=limh→0⁡h=0
B fx=x23
limh→0⁡h23-0h=limh→0⁡h16=0
C fx=xx
limh→0⁡hh-0h2=limh→0⁡hh=1, if h→0+-1, if h→0-
Does not exist
D fx=sin⁡x
limh→0⁡sin⁡h-0h2=limh→0⁡1hsin⁡hh⇒ does not exist

Hence, the correct answer is options: 'B', 'D'.

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