Question:

Th region which is bounded by the curve , the , and the lines and . Show that the volume of the solid formed when is rotated completely about the x-axis is

Attempt:

Why did I get the answer negative? Where did I go wrong?

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- Apr 25th 2008, 03:36 AMlooi76[SOLVED] Volume of Revolution Question
**Question:**

Th region which is bounded by the curve , the , and the lines and . Show that the volume of the solid formed when is rotated completely about the x-axis is

**Attempt:**

Why did I get the answer negative? Where did I go wrong? - Apr 25th 2008, 03:38 AMMoo
Hello,

Actually, I think that the answer has to be :

As you're bounded with the x-axis, that is to say y=0, you have to put it in the integral..

or not, I don't know :) - Apr 25th 2008, 03:39 AMDanshader
integrating 2/(x+1)^2 gives you -2/(x+1)

your working looks weird O.o"

ok i found the mistake >.<

you squared the function of y wrongly

the integration should be

integration from 1 to 5 of the function 2^2/(x+1)^2

instead of

integration from 1 to 5 of the function (2/(x+1)^2)^2