Question
Find the second-order derivative of the function exsin 5x

Answer

Let y = exsin 5x

$\therefore \frac{{dy}}{{dx}} = {e^x}\frac{d}{{dx}}\sin 5x + \sin 5x\frac{d}{{dx}}{e^x}$

$= {e^x}\cos 5x\frac{d}{{dx}}5x + \sin 5x.{e^x} $ $= {e^x}\cos 5x \times 5 + {e^x}\sin 5x$

= ex(5 cos 5x + sin 5x)

$\Rightarrow \frac{{{d^2}y}}{{d{x^2}}} = {e^x}\frac{d}{{dx}}\left( {5\cos 5x + \sin 5x} \right) + \left( {5\cos 5x + \sin 5x} \right)\frac{d}{{dx}}{e^x}$

$= {e^x}\left[ {5\left( { - \sin 5x} \right) \times 5 + \left( {\cos 5x} \right) \times 5} \right] $ + (5 cos 5x + sin 5x)ex

= ex(-25 sin 5x + 5 cos 5x + 5 cos 5x + sin 5x)

= ex(10 cos 5x - 24 sin 5x)

= 2ex(5 cos 5x - 12 sin 5x)

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free