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myko
 one year ago
Best ResponseYou've already chosen the best response.0multiplying everything by 36 you get; 2x^2+y^2=36 which maybe more clear for you, :)

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0hey! :) i tried this: x²/16 + y²/36 = 1 (1/16)x² + (1/36)y² = 1 2(1/16)x + 2(1/36)yy' = 0

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0but so far im not sure what to do after because i know i get x/8 + ?? but then i can't really multiply (1/36) 2y*dy/dx ?

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0isn't the point here to find dy/dx?

myko
 one year ago
Best ResponseYou've already chosen the best response.0let \(F(x,y)=2x^2+y^2=36\) then: \(dF(x,y)=4xdx+2ydy=0\) from here: \(y'=dy/dx=4x/2y=2x/y\)

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0howd you get this?? let F(x,y)=2x2+y2=36

myko
 one year ago
Best ResponseYou've already chosen the best response.0\(dF(x,y)\) is colled full differential it is: \(dF(x,y)=F_xdx+F_ydy\)

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0i never seen that before

myko
 one year ago
Best ResponseYou've already chosen the best response.0\(F_x\) is partial derivative respect to x

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0i know those, but where are the numbers coming from?

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0in what order, where did you take them?

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0i know they're given but how did you get 36 on the other side. and 2x^2+y^2let F(x,y)=2x2+y2=36

myko
 one year ago
Best ResponseYou've already chosen the best response.0ok, other way: think that y is actualy a function of x, so it is y=y(x). Then: \(2x^2+y(x)^2=36\) now we differentiate keeping this in mind 4x+2yy'=0 now just solve for y'

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0yes i know when to differentiate but how did you change the function to that

myko
 one year ago
Best ResponseYou've already chosen the best response.0Ya you right I made a mistake. I was treating 36 like 32, :). Shold be. Rest of steps same. dw:1381788857534:dw

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0i know I was going to tell you.

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0you can't have 36 at the end.

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0i saw a different way on yahoo, would be be able to help me with this one x²/16 + y²/36 = 1 (1/16)x² + (1/36)y² = 1 2(1/16)x + 2(1/36)yy' = 0 (x/8) + (y/18)y' = 0 (y/18)y' = (x/8) y' = (x/8)/(y/18) y' = (x/8)(18/y) y' = (9x/4y) y'(2) = (9(2))/(4(5.2)) y'(2) = 18/20.8 y'(2) = 9/10.4 y'(2) = 0.865

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0I'm not really sure how they got the 4th step :/.... this part> + (y/18)*dy/dx ??

myko
 one year ago
Best ResponseYou've already chosen the best response.02(1/16)x + 2(1/36)yy' = 0 (2/16)x+(2/36)yy'=0 (x/8) + (y/18)y' = 0

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0yes my question is exactly what you wrote up there .... dw:1381789520628:dw(x/8) + (y/18)y' = 0

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0how did it get simplified to y/18*dy/dx?

myko
 one year ago
Best ResponseYou've already chosen the best response.0your answer is same, just simplify 2 in numerator with 36 in denominator

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0thanks! :) i dontkknow why i missed that silly stuff.

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0then i plug in for x and y and find the common denominators rights?

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0wait we're not done yet! :(

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0the question is asking y'(1)

myko
 one year ago
Best ResponseYou've already chosen the best response.0y' = (9x/4y) so: substitute x=1, y=5.80948 y'(1)=9/4(5.80948)

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0okay i got dy/dx=.387298

mathcalculus
 one year ago
Best ResponseYou've already chosen the best response.0got it thanks @myko :))!
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