Find `(d^2y)/(dx^2)` if
`y=e^x.tanx`

Explanation

Given, `y=e^x.tanx`
`therefore dy/dx=e^x.sec^2x+e^x.tanx`[Applying `d/dx(e^x)=e^x`]
`therefore (d^2y)/(dx^2)=e^x.2secx.secxtanx+e^x.sec^2x+e^x.sec^2x+e^xtanx`
`=2e^xsec^2x(1+tanx)+e^xtanx`