Answer
One way of showing that $\dfrac{1}{x} + \dfrac{1}{y}$ is not equal to $\dfrac{1}{x+y}$ is by letting $x=2$ and $y=2$.
See the explanation below.
Work Step by Step
In general, $\dfrac{1}{x} +\dfrac{1}{y} \ne \dfrac{1}{x+y}$.
To illustrate this, let $x=2$ and $y=2$ to have:
$\dfrac{1}{2} + \dfrac{1}{2} \ne \dfrac{1}{2+2}
\\\dfrac{2}{2} \ne \dfrac{1}{4}
\\1 \ne \dfrac{1}{4}$
