ass="o">-</span><span class="nx">negative</span><span class="w"> </span><span class="nx">x</span><span class="p">,</span><span class="w"> </span><span class="k">and</span><span class="w"> </span><span class="nx">has</span><span class="w"> </span><span class="nx">the</span>
<span class="nx">probability</span><span class="w"> </span><span class="nx">density</span><span class="w"> </span><span class="nx">function</span>

<span class="w">    </span><span class="nx">f</span><span class="p">(</span><span class="n