
                    
  <div class="problem">
    <div class="marginpar">
      Use <a href=
      "http://sagecell.sagemath.org/?z=eJxL06jQqdS0rYgz0jbSqtCq1DbWqowz4uXi5SooyswrUVAKyUhVSEktyixLLMksS1XILFYCSabppWSmpWlognUDAKNdE5Y=&amp;lang=sage">
      Sage</a> to check your answers. <span class="bmw">See 14.3:
      1-40 for more practice.</span><span class="larsonfive">See
      Larson 13.3:9&ndash;40 for more practice in doing partial
      derivatives.</span> I strongly suggest you practice a lot of
     