Evaluate the following integral:

Let us assume


Adding – 1 and + 1





Let



Thus I = I1 – I2 …….equation 1


Solving for I1




since


I1 = [tan – 1(∞) – tan – 1(0)]


I1 = π/2 ……….equation 2


Solving for I2



Let .....…..equation 3




a + b = 0; a + c = 1; b + c = 0


solving we get


a = c = 1/2


b = – 1/2


substituting the values in equation 3




Thus substituting the values in I2, thus




Solving :



Let 1 + x2 = y


2xdx = dy


For x = ∞


y = ∞


For x = 0


y = 0


substituting values




Thus




……….equation 4


Substituting values equation 2 and equation 4 in equation 1


Thus


I = I1 – I2


I = π/2 – π/4


I = π/4


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