Implicit Differentiation

  • #1
[SOLVED] Implicit Differentiation

-4x^2+3xy+4y^3=-328

This is at the point (3,-4)
and i am trying to find m


Homework Equations





The Attempt at a Solution



here is my work

-4x^2+3xy+4y^3=-328
-8x+3xy'+3y+12y^2y'=0
-8x+3y=-3xy'-12y^2y'
-8x+3y=[-3x-12y^2]y'
y'=(-8x+3y)/(-3x-12y^2)
plug in x=1,y=3 then solve and get
m=-12/67
can you find the error?
It would be very much appreciated
thank you.
 
Last edited:

Answers and Replies

  • #2
nicksauce
Science Advisor
Homework Helper
1,272
5
Try plugging in the values to your final expression again.
 
  • #3
0h, the answer is correct, it just needs to be not negative, thank you. i was about to go crazy
 
Last edited:
  • #4
cristo
Staff Emeritus
Science Advisor
8,107
73
0h, the answer is correct, it just needs to be negative, thank you. i was about to go crazy
I don't agree that your numerical answer is correct, regardless of the sign.
 
  • #5
yeah, its correct i just checked. thankx for helping me:smile:
 
  • #6
cristo
Staff Emeritus
Science Advisor
8,107
73
yeah, its correct i just checked. thankx for helping me:smile:
Well, maybe it is now you've changed the point to (3,-4)!
 

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