Find dy/dx by implicit differentiation.
6 cos(9x) sin(6y)=9
Pls help me check my answer, i don't know where it's wrong

6(-9 sin9x sin6y + cos9x 6 dy/dx cos6y) =0
-54 sin9x sin6y + 36 dy/dx cos9x cos6y=0
Dy/dx= (54sin9xsin6y)/(36cos9xcos6y)
Dy/dx= (3/2)(tan9xtan6y)

Question

Find dy/dx by implicit differentiation. 
6 cos(9x) sin(6y)=9
 Pls help me check my answer, i don't know where it's wrong

6(-9 sin9x sin6y + cos9x 6 dy/dx cos6y) =0 
-54 sin9x sin6y + 36 dy/dx cos9x cos6y=0 
Dy/dx= (54sin9xsin6y)/(36cos9xcos6y) 
Dy/dx= (3/2)(tan9xtan6y)

phi · Answer

looks ok to me.  the only thing I would change is use *implicit differentiation*
-9 sin9x sin6y dx + cos9x 6 cos6y dy  =0 
(and I would have divided both sides by 6 to make the 6 go away)

anonymous · Answer

so it means Dy/dx= (3/2)(tan9xtan6y) is still the answer? I do an online assignment  and the system said that it was wrong T_T

anonymous · Answer

ah sorry, it's ok now I have to type (3/2)(tan(9x)tan(6y)) >.<