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martindcx1e
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10-18-2007, 04:44 AM
Post subject: OK who wants to do a calculus problem?
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#1 (permalink)
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4-of-a-Kind
Join Date: Mar 2005
Posts: 3,614
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Find dy/dx (or just call it y') by implicit differentiation.
tan(x/y) = x + y
I see the answer but I need to understand it. Can someone explain it well plz? I did the following so far:
1) Derivative of tan(x/y) = [sec(x/y)]^2 * [(y-xy')/y^2]
is equal to
2) Derivative of x + y = 1 + y'
Is this right so far? If so then I'm just having trouble simplifying the way the book does I guess.
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gabe
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what exactly is given (not the answer), and what exactly do you need to show
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gabe
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Moderator
Join Date: Dec 2004
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"Is this right so far?"
yes
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martindcx1e
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4-of-a-Kind
Join Date: Mar 2005
Posts: 3,614
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Quote:
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Originally Posted by gabe
what exactly is given (not the answer), and what exactly do you need to show
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tan(x/y) = x + y is given
answer in back of book is...
y' = [ysec^2(x/y)-y^2] / [y^2 + xsec^2(x/y)]
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Wikipedia is the best thing ever. Anyone in the world can write anything they want about any subject. So you know you are getting the best possible information.
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mcatdog
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4-of-a-Kind
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Quote:
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Originally Posted by martindcx1e
Quote:
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Originally Posted by gabe
what exactly is given (not the answer), and what exactly do you need to show
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tan(x/y) = x + y is given
answer in back of book is...
y' = [ysec^2(x/y)-y^2] / [y^2 + x sec^2(x/y)] |
Are you sure you typed that in correctly because I'm getting the same answer except with the bold term not there at all.
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martindcx1e
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4-of-a-Kind
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i typed it correctly mcat
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Wikipedia is the best thing ever. Anyone in the world can write anything they want about any subject. So you know you are getting the best possible information.
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gabe
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Moderator
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so all you need to do is solve for y' in the equatino you wrote in (1)
[sec(x/y)]^2 * [(y-xy')/y^2] = 1 + y'
so distribute the left side, then move the term with the y' in it to the right side
ill post it out if that doesnt help
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mcatdog
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4-of-a-Kind
Join Date: Oct 2005
Location: St. Louis
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never mind their answer is correct
try setting that funky secant expression to equal K and then simplify it that'll make things easier
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martindcx1e
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4-of-a-Kind
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ah thanks mcat that worked out nicely
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Wikipedia is the best thing ever. Anyone in the world can write anything they want about any subject. So you know you are getting the best possible information.
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WildBobAA
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4-of-a-Kind
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MATH FUCK YEAH
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lolzzz_321
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NO YOU
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what you know bout math?
http://youtube.com/watch?v=Ooa8nHKPZ5k
FEAT TI 84
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