Find the The Slopes of the tangent and the normal to the following curves at the indicated points :
$x y=6$ at $(1,6)$
Given:
$x y=56$ at $(1,6)$
Here we have to use the product rule for above equation.
If $u$ and $v$ are differentiable function, then
$\frac{\mathrm{d}}{\mathrm{dx}}(\mathrm{UV})=\mathrm{U} \times \frac{\mathrm{dV}}{\mathrm{dx}}+\mathrm{V} \times \frac{\mathrm{dU}}{\mathrm{dx}}$
$\frac{\mathrm{d}}{\mathrm{dx}}(\mathrm{xy})=\frac{\mathrm{d}}{\mathrm{dx}}(6)$
$\Rightarrow \times \times \frac{\mathrm{d}}{\mathrm{dx}}(\mathrm{y})+\mathrm{y} \times \frac{\mathrm{d}}{\mathrm{dx}}(\mathrm{x})=\frac{\mathrm{d}}{\mathrm{dx}}(5)$
$\therefore \frac{\mathrm{d}}{\mathrm{dx}}($ Constant $)=0$
$\Rightarrow \mathrm{x} \frac{\mathrm{dy}}{\mathrm{dx}}+\mathrm{y}=0$
$\Rightarrow \mathrm{x} \frac{\mathrm{dy}}{\mathrm{dx}}=-\mathrm{y}$
$\Rightarrow \frac{\mathrm{dy}}{\mathrm{dx}}=\frac{-\mathrm{y}}{\mathrm{x}}$
The Slope of the tangent at $(1,6)$ is
$\Rightarrow \frac{d y}{d x}=\frac{-6}{1}$
$\Rightarrow \frac{d y}{d x}=-6$
$\therefore$ The Slope of the tangent at $(1,6)$ is $-6$
$\Rightarrow$ The Slope of the normal $=\frac{-1}{\text { The Slope of the tangent }}$
$\Rightarrow$ The Slope of the normal $=\frac{-1}{\left(\frac{\mathrm{d} y}{\mathrm{dx}}\right)}$
$\Rightarrow$ The Slope of the normal $=\frac{-1}{-6}$
$\Rightarrow$ The Slope of the normal $=\frac{1}{6}$