I'm doing differential equations and got stuck on this part.

How do I solve for y if I have the equation:

-siny = x^2 + C

Thanks

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- Sep 13th 2010, 07:29 PMjzelltSolve for y...
I'm doing differential equations and got stuck on this part.

How do I solve for y if I have the equation:

-siny = x^2 + C

Thanks - Sep 13th 2010, 07:34 PMpickslides
- Sep 13th 2010, 09:51 PMEducated
- Sep 13th 2010, 09:57 PMpickslides
- Sep 13th 2010, 10:00 PMEducated
Maybe this is why I'm still in high school.

Just ignore me then... I haven't learnt those things yet.

EDIT:

Wait...

$\displaystyle \displaystyle c\in \mathbb{R}$

c is and element of a real number...

Isn't -c a real number? Why isn't -c allowed? - Sep 13th 2010, 10:16 PMpickslides
- Sep 14th 2010, 03:34 AMHallsofIvy
Since C is an

**arbitrary**real number, it doesn't matter whether C is positive or negative and it doesn't matter whether we call it "C" or "- C". The same thing happens often with exponentials. If you have a solution to an equation of the form $\displaystyle e^{x+ C}$ where C is an arbitrary constant, you can write that as $\displaystyle e^{x+ C}= e^C e^x$ or simply as $\displaystyle C e^x$. Strictly speaking, we should use a different symbol, say C' with the explanation that $\displaystyle C'= e^C$ but typically, knowing that they are both just arbitrary numbers, that is not done.