hi,
given f(x,y) = cos(x+y) - sin(x-y),

find ∂f/∂x.

is my work right?
first, convert to
cos x cos y - sin x sin y -sin x cos y + cos x sin y

∂f/∂x= -sin x cos y - cos x sin y - cos x cos y - sin x sin y

or

∂f/∂x = -sin(x+y) - cos(x-y)

which is right?

thanks
stupid

 

hi,
given f(x,y) = cos(x+y) - sin(x-y),

find ∂f/∂x.

is my work right?
first, convert to
cos x cos y - sin x sin y -sin x cos y + cos x sin y

∂f/∂x= -sin x cos y - cos x sin y - cos x cos y - sin x sin y

or

∂f/∂x = -sin(x+y) - cos(x-y)

which is right?

thanks
stupid

They are both right.

 

They are both right.

i juz realised my silly question...thanks

stupid