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#1 2008-02-25 05:21:14
- frem
- Member
- Registered: 2008-02-23
- Posts: 3
confusing...
I've answered an exact equation. The question is:
(x-y³ +y² sinx) dx = (3xy²+2y cosx) dy = 0.
In the end, I got (x²/2)-y² cosx - y³x=C but the answer in the answer sheet is opposite sign to my answer. Does my answer can be accepted?
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#2 2008-02-27 03:02:04
- mathsyperson
- Moderator
- Registered: 2005-06-22
- Posts: 4,900
Re: confusing...
I would say so. Multiplying both side of what you have by -1 gives [Their LHS] = -C.
But C is an arbitrary constant, so changing its sign doesn't alter that it's an arbitrary constant.
So you could just as easily write [Their LHS] = C.
So your answer is equivalent to the one they give.
Why did the vector cross the road?
It wanted to be normal.
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