stitution, see section 5.5 and
      5.6. \\ For practice with integration by parts, see section
      8.1.</div>
      Compute $\ds\int x\sqrt{x^2+4}dx$.
  </div>

  <div class="problem">
    Compute $\ds\int x\sin 2x dx$.
  </div>

  <div class="problem">
    Compute $\ds \int \arctan x dx$.
  </div>

  <div class="problem">
    Compute $\ds \int x^2 e^{3x} dx$.
  </div>

</section></section><section>
  <h1>Differentials</h1>
  <p>The derivative of a function gives us the
  slope of a tangent line to that