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volume of revolution question - HSN forum

# volume of revolution question

### #1bb98

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Posted 25 January 2007 - 09:58 PM

can some1 help me with this question please?

you're given the volume of revolution as 40pi and you're to find the value of t (the upper limit) which gives this in the equation y = x^2 + 4. the lower limit is 1 and t > 1.

=> 40pi = int (pi.(x^2 +4)^2) dx limits: t, 1

thnx for any help

### #2dfx

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Posted 26 January 2007 - 02:24 PM

Work out the indefinite integral, plug in limits for t and 1 in place of x, this whole expression is equal to 40pi, and so finally solve for t. Remember you can take out the pi as a constant out of the integral sign which should make it neat. Sorry for not tex formatting guys, in a hurry.

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