Question

dy/dx of cos(x+y)=x.

Answer 1

I came up with - (1+sin(x+y))/(sin(x+y)) but it doesn't really seem right? If you can help, please do. :)

Answer 2

\[\cos(x+y)=x\]
\[\cos^{-1} x=x+y\]
\[y=\cos^{-1} x-x\]
\[dy/dx=(\cos^{-1} x-x)\prime\]

Answer 3

\[dy/dx=-1/\sqrt{1-x^2}-1\]

Answer 4

i hope i am not doing any mistake...

Answer 5

if this is right, fan me plz.

Answer 6

You probably used implicit differentiation heist.
If you did, then you'd get your answer (and I got the same thing).
You could also check it here.
http://www.wolframalpha.com/input/?i=derivative+of+cos%28x+%2B+y+%29+%3D+x

eDadou, I'm not sure why your method doesn't give the same answer.
I think it might have to do with taking the arccosine of both sides,
since that then restricts the domain over which x can vary.

Answer 7

yeah probably.