Choose the correct answer.
∫1ex+e−x dx is equal to(a) tan−1ex+C(b) tan−1e−x+C (c) log (ex−e−x)+C(d) log (ex+e−x)+C
tan−1(xy)−tan−1(x−yx+y) is equal to a) π2 b) π3 c) π4 d) −3π4
tan−1ab−tan−1(a−ba+b) =