Let S be the set of points where the function , f x = | 2 - | x - 3 | , x ∈ R , is not differentiable. Then ∑ x ∈ S f f x is equal to

Question

Let S be the set of points where the function , f x = | 2 - | x - 3 | , x ∈ R , is not differentiable. Then ∑ x ∈ S f f x is equal to,

MARKS App · Accepted Answer

Check non-differentiability of function, we get, ∵ f x is non differentiable at x = 1 , 3 , 5 ∑ f f x = f f 1 + f f 3 + f f 5 = 1 + 1 + 1 = 3