## DLS 2 years ago x^3+y^3+3axy=0 dy/dx=?

1. DLS

$\LARGE 3x^{2}+3y^{2} \frac{dy}{dx}-3ax=0$ this gives..finally.. $\LARGE \frac{dy}{dx}=\frac{x(a-x)}{y^{2}}$ I doubt this because im quite unsure about the derivative of 3axy,we are differentiating wrt x or y? if its x then 3ay(dx//dx) not sure..

2. DLS

@hartnn

3. hartnn

you'll need product rule for 3axy

4. DLS

I thought product rule was used for function times function

5. DLS

thats a variable,isn't it

6. hartnn

y is the function of x, x is the function of x.

7. DLS

:O

8. hartnn

(xy)' = x'y+xy' = y+xy'

9. DLS

so how will we find for 3axy?

10. hartnn

3a (y+xy')

11. DLS

$\LARGE 3ay(\frac{dx}{dx}) |||| 3ax(\frac {dy}{dx})$

12. hartnn

dx/dx=1

13. DLS

yeah!

14. hartnn

and i assume ||| is +

15. DLS

yes

16. DLS

thats it?:O

17. hartnn

so, dy/dx will change..

18. DLS

what do u mean?

19. hartnn

i mean recalculate dy/dx

20. DLS

$\LARGE \frac{dy}{dx}= \frac{-3(ay+x^{2})}{3(y^{2}-ax)}$

21. hartnn

-ax ?

22. DLS

sorry + printing mistake :P

23. hartnn

then ok.

24. DLS

:D