Question

second derivative of a trig function
cos(xy) + x^7=y^7

Answer 1

not sure what to do with the (xy) I believe it is chain rule

Answer 2

yeah, it is
[cos (xy) ]' = -sin (xy) [xy]' = ....

Answer 3

does the (xy)' go in front of the trig function (like a constant)?

Answer 4

it gets multiplied with -sin xy
and its not constant

Answer 5

I think I need to go and read my book some more. I have not seen this type of problem in a very long time.

Answer 6

just chain rule and product rule is required here...

Answer 7

did not mean to run off, I went to go look for my book

Answer 8

no problem :)

Answer 9

or let me write down what I think it is, stop me if I am incorrect
I do write things in certain order just because I confuse myself otherwise

Answer 10

-sin(xy)[y+y'x] + 7x^6=7y^6y'

Answer 11

now I need to distribute -sin(xy) correct

Answer 12

yes,
basically to isolate y'

Answer 13

ok got it, I checked the key and my solutions match up. Thanks your explanation was exactly what I needed.

Answer 14

you're welcome ^_^