# Homework Help: Silly Question Maybe?

1. Jan 13, 2014

### AstroIreland

1. The problem statement, all variables and given/known data

I have a very simple question I am having problems with.

2. Relevant equations

n= C/V

3. The attempt at a solution

Hey guys,

This is a very simple equation indeed. I am a mature student and starting up in physics.
My mathematics is terrible. So please don't laugh. I can seem to integrate and differentiate but for some reason, I have forgotten something really really really stupid.

I rearranged the above formula earlier and to solve for v and I came up with Cn=V.

I dont know why I am doing that and this, I had no problem before.

So my question is, when changing sides of an equation, how do I know which to move from one side to the other and in what order.

Do i start with numerator or denominator. And if so, what order.

I have exams coming up and im in a divorce currently and really really simple stuff has completely slipped from my brain. For obvious reasons, I cant ask this question at my university.

I am in a bit of a panic.

2. Jan 13, 2014

### Staff: Mentor

Multiply both sides by V, and then divide both sides by n.

3. Jan 13, 2014

### AstroIreland

Cheers, but why do you move the v first and not the C???

Is it because its the bigger number or do you always move the denominator first and solve in more steps?

4. Jan 13, 2014

### AstroIreland

like why wouldn't you just move the C first??!

Thanks

5. Jan 13, 2014

### AstroIreland

And say for example I am using the Snells law formula where there is a fraction on each side of the equation.
How do I know when changing sides whether to add to the numerator or denominator? thanks.

6. Jan 13, 2014

### AstroIreland

No worries, cross multiplication was what im looking for.

Can you believe i made it to second year astro in the top 50 uni's in the world???!

Jeeze... exams do funny things to you.

Thanks mate.

Last edited by a moderator: Apr 29, 2014