Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
$y=\sqrt{x^{3}}$ at $x=4$
Given:
$y=\sqrt{x^{3}}$ at $x=4$
First, we have to find $\frac{d y}{d x}$ of given function, $f(x)$,i.e, to find the derivative of $f(x)$
$y=\sqrt{x^{3}}$
$\therefore \sqrt[n]{x}=x^{\frac{1}{n}}$
$\Rightarrow y=\left(x^{3}\right)^{\frac{1}{2}}$
$\Rightarrow y=(x)^{\frac{3}{2}}$
$\therefore \frac{d y}{d x}\left(x^{n}\right)=n \cdot x^{n-1}$
The Slope of the tangent is $\frac{d y}{d x}$
$\frac{\mathrm{dy}}{\mathrm{dx}}=\frac{3}{2}(\mathrm{x})^{\frac{3}{2}-1}$
$\Rightarrow \frac{\mathrm{dy}}{\mathrm{dx}}=\frac{3}{2}(\mathrm{x})^{\frac{1}{2}}$
Since, $\mathrm{x}=4$
$\Rightarrow\left(\frac{\mathrm{dy}}{\mathrm{dx}}\right) \mathrm{x}=4=\frac{3}{2}(4)^{\frac{1}{2}}$
$\Rightarrow\left(\frac{d y}{d x}\right) x=4=\frac{3}{2} \times \sqrt{4}$
$\Rightarrow\left(\frac{d y}{d x}\right) x=4=\frac{3}{2} \times 2$
$\Rightarrow\left(\frac{d y}{d x}\right) x=4=3$
$\therefore$ The Slope of the tangent at $x=4$ is 3
$\Rightarrow$ The Slope of the normal $=\frac{-1}{\text { The Slope of the tangent }}$
$\Rightarrow$ The Slope of the normal $=\frac{-1}{\left(\frac{d y}{d x}\right) x=4}$
$\Rightarrow$ The Slope of the normal $=\frac{-1}{3}$