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Question on Exact differential

The question is to show that the differential 1/xdx+tan(y)dy is exact, which i've done fine and then to find the function f(x,y) by integration, which is the bit i'm stuck on, I've taken all the usual steps but my final answer seems to be wrong. Im getting that f(x,y)= ln(x/cos(y))+c but the answer is given as ln(cxcos(y)) on the tutorial sheet, anyone able to help?

Reply 1

Smaug123

Original post by ElChapo

You've slipped a minus sign somewhere, but otherwise you're right - remember that log(x)+c = log(A x) for some A, so the constant is just expressed differently.