Mathematics
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OpenStudy (anonymous):
volume of cylindrical shells (calculus):
y^2=x, x=2y rotate about y axis
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OpenStudy (anonymous):
bro whats the base equation again, something like pi int .... of the derivative squared?
OpenStudy (anonymous):
idk if that matters
OpenStudy (anonymous):
i have my integral calculus last semester.
OpenStudy (anonymous):
y=+or- sqrtx , y=x/2 to make it simpler
OpenStudy (anonymous):
come on guys, this isnt that hard.
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OpenStudy (anonymous):
wait for a while, i'm solving it.
OpenStudy (anonymous):
what is really the given? it is lacking.
OpenStudy (anonymous):
thats it
OpenStudy (anonymous):
really?
OpenStudy (anonymous):
"find the volume of the solid obtained by rotating the regions bounded by the curves about the specified line.
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OpenStudy (anonymous):
you have to find the point where the two curves meet, and then solve the integral from 0 to that point
OpenStudy (anonymous):
they meet at (0,0)
OpenStudy (anonymous):
got it.
OpenStudy (anonymous):
thats one yes, and then they cross again
OpenStudy (anonymous):
the answer is
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OpenStudy (anonymous):
8pi over 3
OpenStudy (anonymous):
where do the two curves cross?
OpenStudy (anonymous):
the limits are 0 and 2.
OpenStudy (anonymous):
how
OpenStudy (anonymous):
just substitute x=y^2 to x=2y
that will become, y^2-2y=0
y(y-2)=0
y=0
y=2
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OpenStudy (anonymous):
okay, let me double check now
OpenStudy (anonymous):
i had a mistake, the answer must be 10pi/3
OpenStudy (anonymous):
almost have it
OpenStudy (anonymous):
okay,
i have the solution but i have a hard time encoding it.
OpenStudy (anonymous):
whats (2^1.5)/(2/3) -1
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OpenStudy (anonymous):
i dont have my calculator :/
OpenStudy (anonymous):
3.242640687
OpenStudy (anonymous):
okay thats what i got... where did you get pi from?
OpenStudy (anonymous):
im looking in the back of the book for the answer to see whos right.
OpenStudy (anonymous):
2pi integral of (x^1/2-x/2)dx
2pi (x^3/2)/(3/2)-x^2/4, substitute x=2
2pi(2^3/2)(2/3)-2^2/4
2pi(4(2/3)-1)
2pi(8/3 - 1)
2 pi (5/3)
(10pi)/3
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OpenStudy (anonymous):
okay i did it waaaay wrong haha
OpenStudy (anonymous):
back of the book says 64pi/15
OpenStudy (anonymous):
is it correct now?
OpenStudy (anonymous):
is it the answer on the book?
OpenStudy (anonymous):
64pi/15, so its close
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OpenStudy (anonymous):
okay im too tired for this, thanks for the help
OpenStudy (anonymous):
you are welcome, actually i can explain it, i think i just miss some terms in my solution. by the way, do you have skype account?