Q.

Let f(x)=|sinx|. Then

1 f is everywhere differentiable  
2 f is everywhere continuous but not differentiable at x=nπ, n∈Z  
3 f is everywhere continuous but not differentiable at x=(2n+1)π2, n∈Z  
4 None of these  

Ans.

(2)

Ans.      f is everywhere continuous but not differentiable at x=nπ, n∈Z

Explanation:

We have,  f(x)=|sinx|

We know that |x| and sinx are continuous for all real x.

So,  |sinx| is also continuous for all real x.

Since, |x| is non-differentiable at x=0

therefore, |sinx| is non-differentiable when sinx=0  or  x=nπ, n∈Z

Hence, f(x) is continuous everywhere but not differentiable at x=nπ, n∈Z.