Thread: Solve 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

Originally Posted by jzellt

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

Originally Posted by pickslides

Shouldn't it be minus c as well?

Here's what I got:







OR

Originally Posted by Educated

Shouldn't it be minus c as well?

Its a constant , why should it be negative?

Maybe this is why I'm still in high school.

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


EDIT:

Wait...



c is and element of a real number...

Isn't -c a real number? Why isn't -c allowed?

Originally Posted by Educated

c is and element of a real number...

Therefore can be positive or negative.

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 where C is an arbitrary constant, you can write that as or simply as . Strictly speaking, we should use a different symbol, say C' with the explanation that but typically, knowing that they are both just arbitrary numbers, that is not done.