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Mathematics 17 Online
OpenStudy (lukecrayonz):

Could anyone help me with implicit differentiations?

OpenStudy (lukecrayonz):

Differentiate implicity to find dy/dx, then find the slope of the curve at the point. y^2-x^3=1 (2,-3)

OpenStudy (anonymous):

i'll give you an example \[3x^2 + y^2 = 5 \rightarrow 6x + 2yy' = 0\]

OpenStudy (lukecrayonz):

@jim_thompson5910

OpenStudy (anonymous):

differentiate both sides. remember when you differentiate y with respect to x, you must put dy/dx (or y', whichever convention you like) in the above example \[6x + 2yy' = 0 \rightarrow 2yy' = -6x \rightarrow y' = -\frac{ 3x }{ y }\] and if we know a point, like (2, -3), we can determine the slope, y', by the above equation

OpenStudy (anonymous):

treat y as an unknown function y(x). therefore, you must always apply chain rule. for your example: treat y^2 as (y(x))^2. the derivative of that is 2y(x)*y'(x), which can be written more compactly as 2y*y'. you will then want to put y' alone on one side. to find y' = implicit derivative

OpenStudy (lukecrayonz):

@Euler271 could you please help me? Assignment is due at 12 and I have no idea what I am doing

OpenStudy (lukecrayonz):

Like I will definitely have to learn this, but to learn this in 30 minutes and do the assignment is just too much:(

OpenStudy (anonymous):

yes \[y^2 - x^3 = 1\] differntiate all with respect to x:\[2y*y' - 3x^2 = 0\]\[y' = \frac{ 3x^2 }{ 2y }\] y' is the derivative function [the slope function]. plug in (x, y) = (2, -3)\[y' = \frac{ 3(2)^2 }{ 2(-3) } = -2\]

OpenStudy (lukecrayonz):

Okay and for this? http://gyazo.com/3ff8663c8ec5e6d9050f88e30b79238b

OpenStudy (anonymous):

2 is right lol

OpenStudy (lukecrayonz):

woohoo that was honestly a guess hahaha

OpenStudy (lukecrayonz):

And last one I think http://gyazo.com/649bb6d25636232b40bc1a3ac3e5a253

OpenStudy (anonymous):

C: 4.8

OpenStudy (lukecrayonz):

How so? I finished so i'd like to learn:)

OpenStudy (anonymous):

we use the relationship of the length of the ladder and the wall (Pythagorean Theorem) |dw:1382326487876:dw| \[\frac{ d }{ dt }(L^2) = \frac{ d }{ dt }(x^2 + y^2)\]\[2L*L' = 2x*x' + 2y*y'\]L' = 0 beause the length of the ladder does not change dx/dt = x' and dy/dt = y' \[2(13)*0 = 2(5)dx/dt + 2(12)(-2)\]\[0 = 10dx/dt - 48\]\[\frac{ dx }{ dt } = 4.8\]

OpenStudy (anonymous):

great. the drawing didn't work

OpenStudy (lukecrayonz):

Haha it's okay. Look at my newest question please, Hawk Crimson has been writing for like 10 minutes now.

OpenStudy (anonymous):

|dw:1382326911888:dw|

OpenStudy (anonymous):

the answer to that one is:\[\frac{ dy }{ dx } = y' = \frac{ 3x^2 +y^2 - 2xy - 1 }{ 1 - 2xy + x^2 + 3y^2 }\]

OpenStudy (lukecrayonz):

To this?:O http://gyazo.com/d2824d641a3ef9e635f1e09fd2cc13ba

OpenStudy (anonymous):

yes

OpenStudy (lukecrayonz):

But that's not an option :(

OpenStudy (anonymous):

lol ill simplify it i guess

OpenStudy (anonymous):

if its due live pick C

OpenStudy (anonymous):

if you have time. give me a sec

OpenStudy (anonymous):

actually B

OpenStudy (lukecrayonz):

I don't haha, times up! I got an 80 since I got that wrong, but whatever. Learning this kind of stuff within an hour is difficult >_< but B was wrong.

OpenStudy (anonymous):

then c lol

OpenStudy (anonymous):

not bad. do you have the answer?

OpenStudy (lukecrayonz):

Nope :(

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