Q.

For the function f(x)=esin|x|–|x|, x∈R, consider the following statements:

Statement I: f is differentiable for all x∈R.

Statement II: f is increasing in (–π,–π2).

In the light of the above statements, choose the correct answer from the options given below:          [2026]

1 Both Statement I and Statement II are true  
2 Both Statement I and Statement II are false  
3 Statement I is true but Statement II is false  
4 Statement I is false but Statement II is true  

Ans.

(1)

f(x)=esin|x|–|x|, x∈R

For Statement I

For x≥0, f(x)=esinx–x

RHD at x = 0

f'(0+)=e0.1–1=0

For x<0, f(x)=e–sinx+x

LHD at x = 0

f'(0–)=–e0.1+1=0

LHD = RHD at x = 0

∴  Statement I is true

For Statement II

f'(x)=1–e–sinx.cosx         [∵  x∈(–π,–π2)]

Since, –e–sinx.cosx is +ve for given x.

So, f'(x)=1+(a '+ve' value)

f'(x)>0 for (–π,–π2)

So Statement II is true.