Evaluate ∫1x21+x2dx
−x2+1x+c
−xx2+1+c
−x2-1x+c
None of these
Let x = tanθ or dx = sec2θ dθ
∴ ∫1x21+x2dx=∫sec2θdθtan2θsecθ =∫cosecθcotθdθ =−cosecθ+c =−x2+1x+c