Evaluate: `inttan2xtan3xtan5xdx`

Explanation

We have given

`int tan2xtan3xtan5xdx`

Let `tan5x=tan(2x+3x)`

As we know that,

`tan(a+b)=(tana+tanb)/(1-tanatanb)`

So,

`tan5x=tan(2x+3x)=(tan2x+tan3x)/(1-tan2xtan3x)`

`tan5x(1-tan2xtan3x)=(tan2x+tan3x)`

...