<p>Just copy the text on this website in the textfield <strong>without</strong> formatting it as code and you will see that it renders as:</p>

<p>\begin{eqnarray} \mbox{output} &amp; = &amp; \left\{ \begin{array}{ll} 0 &amp; \mbox{if } \sum_j w_j x_j \leq \mbox{ threshold} \\ 1 &amp; \mbox{if } \sum_j w_j x_j &gt; \mbox{ threshold} \end{array} \right. \tag{1}\end{eqnarray}</p>

<p>or as a graphic:</p>

<p><img src="https://i.stack.imgur.com/BhNNq.png" alt="enter image description here"></p>

<p>Hence, you simply need to add it into a online or offline LaTeX converter.</p>
