Question

Find the derivatives w.r.t.x:
7 sin x - 4x² cos x

Answer 1

here is ur Answer ✍️✍️

Answer 2

To differentiate the given function in second ,we have to apply UV rule of differentiation

$\begin{lgathered}\frac{d(UV)}{dx} = U \frac{dV}{dx} + V\frac{dU}{dx} \\ \\ here \: let \: U = {x}^{2} \\ \\ V = cos \: x \\ \\\end{lgathered}$

$\frac{d}{dx} (7 \: sin \: x) = 7 \: cos \: x$
$\frac{4d( {x}^{2} \: cos \: x )}{dx} = {x}^{2} \frac{d \: (cos \: x)}{dx} + cos \: x\frac{d {x}^{2} }{dx} \\ \\ = - 4 {x}^{2} sin \: x + 8x \: cos \: x$
$\frac{d}{dx} (7 sin x - 4 {x}^{2} cos x) \\\\= 7 \: cos \: x+ 4 {x}^{2} sin \: x - 8x \: cos \: x$
Hope it helps you.