Concept:The function is a sum of a continuous absolute-value term and a discontinuous greatest-integer term.
Explanation:Let
f(x)=g(x)+h(x), where
g(x)=(∣x∣+∣x−1∣)sinx and
h(x)=[xsinx].
g(x) is continuous in
(−π/2,π/2) because absolute values and sine are continuous.
h(x) is discontinuous whenever
xsinx is an integer, due to the jump of the greatest-integer function.
Find where
xsinx=0: gives
x=0. At
x=0,
h(x)=0, and the function does not jump, so
f is continuous at
0.
Find where
xsinx=1: there is a point
x1 in
(0,π/2) and its symmetric
−x1.
At these two points,
[xsinx] jumps from
0 to
1, so
f is not continuous there. Hence
α=2.
Differentiability fails at the discontinuity points
x1 and
−x1 because the function is not continuous there.
Also check points where
g(x) might be non-differentiable:
x=0 and
x=1 due to absolute values.
At
x=0, left and right derivatives match, so differentiable.
At
x=1, left derivative is
cos1, right derivative is
cos1+2sin1, which are not equal, so
f is not differentiable at
x=1.
Thus points of non-differentiability are
x1,
−x1, and
1, giving
β=3.
Answer:α+β=2+3=5.