Question

If y^2-2xy=21, then dy/dx at the point (2,-3) is

Answer 1

implicit differentiation
2yy'+0xy-2y-2xy'=0
2yy'-2xy'=2y
yy'-xy'=y
y'(y-x)=y
y'=y/(y-x)

Answer 2

plug in your values

Answer 3

can u explain how u do implicit diff. ?

Answer 4

im kinda bad at it

Answer 5

use the chain rule whenever you take the derivative of y with respect to x:
for example, dy/dx (y^3)=3y^2y'

Answer 6

so when u differentiate, u put y' to show it was differentiated?

Answer 7

dy/dx y=y'

Answer 8

the chain rule is u multiply derivative of inside* outside + inside*derivative of outside, right?

Answer 9

think you are talking about the product rule

Answer 10

oh sorry so how do u use the chain rule?

Answer 11

that wasn't a very good explanation lol
look here
http://en.wikipedia.org/wiki/Chain_rule

Answer 12

so how did u know to use teh chain rule becuase here it isnt a compostion of funtions

Answer 13

think \(y=f(x)\)

Answer 14

\[y^2-2xy=21\]
\[f^2(x)-2xf(x)=521\]

Answer 15

\[2f(x)f'(x)-2f(x)-2xf'(x)=0\] more easily written as
\[2yy'-2y-2xy'=0\]

Answer 16

ok i see that