Question: Find the volume of solid formed by revolving the region bounded by the given function $f(x)$:

$$ Y= 3 – x ;$$ about the $x-$axis.

How do I find the upper and lower limits of integration ?

  • $\begingroup$ Please show your work. $\endgroup$ – PackSciences Feb 20 at 19:08
  • $\begingroup$ $y=3-x$ is a lineare function, for $x=0$ we get $3$ and for $y=0$ we get also $3$ $\endgroup$ – Dr. Sonnhard Graubner Feb 20 at 19:08
  • $\begingroup$ Actually, this is the question given. I wrote it as it is. I know how to apply the formula, I just have no idea how to get the limits. $\endgroup$ – Hala Feb 20 at 19:13
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    $\begingroup$ First of all, use the disk method. The upper limit of integration is going to be $3$ because $3-x=0\implies x=3$. That's the number where the line $3-x$ crosses the x-axis. The lower limit of integration—no idea. It's not entirely clear from your question what it should be. It is poorly formed, I would say. $\endgroup$ – Michael Rybkin Feb 20 at 19:13
  • 1
    $\begingroup$ You need a 3rd element to bound a region when two elements are non-parallel straight lines. A very poorly written question. $\endgroup$ – Phil H Feb 20 at 20:10

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