How do you differentiate this? (2 Viewers)

[Dragonmaster262]

x^2+2xy+3y^2=18

 

[tommykins]

implicit differentiation

 

[annabackwards]

implicit differentiation

Yar.

Remember to use product rule for the "2xy" bit

 

[omgmynameislong]

x^2+2xy+3y^2=18

d(x^2+2xy+3y^2)/dx=d(18)/dx

dx^2/dx + d(2xy)/dx + 3y^2/dx = 0

2x + d(2x)/dx . y + dy/dx . x + d(3y^2)/dy = 0
2x + 2y + xy' + 6y= 0
xy' = -8y - 2x
y'= -8y-2x/x

.....think thats wrong lolol.

 

[lychnobity]

x^2+2xy+3y^2=18

differentiate that:

2x + 2y + 2xy' + 6yy' = 0

y'(2x + 6y) = -2x - 2y



to find the gradient, sub in a point (x,y) blah blah blah

 

[Dragonmaster262]

Thanks guys I just realised that this was implicit differentiation after I posted this thread.

 

[RaxX]

ill do it if you want and scan it up.