title: Mathematica plot is a straight line
body: <p>So I'm trying to knock out this last problem, and I'm following my teacher's guide but my graph seems to still be off, the problem is:</p>
  
  <p>Use the FindRoot command in Mathematica to define an inverse function <code>g(y) to y = f(x) = 3x + tan(x)</code> with the restriction <code>‑pi/2 &lt; x &lt; pi/2</code>.  Use <code>x = tan-1(y)</code> as a starting value.  Then use the Plot command to make a graph of g(y).</p>
  
  <p>This is how I wrote it out:</p>
  
  <pre><code>g[y_] := x /. FindRoot[3 x + Tan[x] == y, {x, ArcTan[y]}]
  
  Plot[g[y], {y, (-Pi/2), (Pi/2)}]
  </code></pre>
  
  <p>I'm not sure exactly what the problem is, but it shows the graph as just being a straight line through the origin. I'm not sure if this is how it's supposed to be (which I assume it's not), but any and all help would be much appreciated!</p>