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
I=∫1ex+e−x=∫1ex+1exdx=∫ex(ex)2+1dxPut ex=t⇒ exdx=dt (∵ ∫ dx1+x2=tan−1x)∴ I=∫ ext2+1dtex=tan−1(t)+C.=tan−1ex+C.
Hence, option (a) is correct.