# Quick algebra question

1. Nov 14, 2014

### christian0710

1. The problem statement, all variables and given/known data
I stated this as a small attached photo, since i still need to learn to write in latex (see photo)

2. Relevant equations
How do you transform the first expression into the next expression (on photo)?

3. The attempt at a solution

#### Attached Files:

• ###### math 1.PNG
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2. Nov 14, 2014

### SteamKing

Staff Emeritus
I'm not sure what 'potens' rules are, but how do you bring anything under the radical sign? What must you do to it first?

Or as an alternate approach, if you add the expressions together under the radical on the RHS and simplify, what do you get?

3. Nov 14, 2014

### christian0710

I'm unsure of that: what must you do to bring something under the radical sign? I'm suck with respect to that trick.

4. Nov 14, 2014

### christian0710

Ohh wait now I get it, if you take the square root of dt^2 then both terms are under the radical :)

5. Nov 14, 2014

### PeroK

I don't have any compehension of what the LHS means. But, in terms of "algebra", the identity is only true if dt is positive.

$\frac{\sqrt{a^2 + b^2}}{c} = \pm \sqrt{\frac{a^2}{c^2} + \frac{b^2}{c^2}}$