# Having a hard time understanding whats asked.

1. Sep 7, 2015

### MidgetDwarf

Taking an intro ODE class. Class just started and we are using a book, that to me, feels like en encrypted alien language. It is hard to read, but to much words and images, not enough layout. I'm more into theorem/proof style books. The book is too chatty. Well anyways.

It is giving problems trying to do my hw sets. For example.

Show that the implicit solution of 2x sin2 ydxx2 + 10 cos ydy = 0 is given by ln x2 + 10+csc y = c:

This is not explained clearly in the book. ( the directions).

Does this mean to just take the implicit derivative of ln x2 + 10+csc y = c and put into the form that contains the DE.

or does this mean to integrate 2x sin2 ydxx2 + 10 cos ydy = 0.

I am leaning on the implicit differentiation.

I already worked out both ways. I am definitely going to get the library and get a book.

2. Sep 7, 2015

### Strum

You should write it using tex. It is hard to read the equations like this.

3. Sep 7, 2015

### micromass

Staff Emeritus
This should be explained in any good ODE book like Ross.

4. Sep 9, 2015

### HallsofIvy

Staff Emeritus
"Show that the implicit solution of 2x sin2 ydxx2 + 10 cos ydy = 0 is given by ln x2 + 10+csc y = c"

I don't know why you would need "directions". It's pretty straightforward English. You could show that by solving the equation and seeing that the given solution is of the type you got but the simpler way is to put that function into the equation and see that the equation is satisfied.

If you were asked to show that x= 2 is a root of $x^3- 6x^2+ 11x- 6= 0$, you could[/b try to solve the equation but it would make more sense to use the fact that you are already given x= 2, substitute that into the equation, and see what you get!