Help Please

BLH

New member
Joined
Aug 4, 2009
Messages
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Hi could you please help with the following: I am taking a summer course and can not figure this out
The copy is poor so I am not sure if it to be written

x=?(R-r)/(R+r)

or x=?(R-r)/(R+r) Note: Square root for the entire fraction of R-r/R+r

I really appreciate your help.

Thanks
BLH
 
You don't say what you are trying to do. If you are supposed to simplify it, you are probably trying to end up with any radical sign in the numerator only. IF that is the case, multiply both numerator and denominator by the denominator. That gives you a perfect square in the denominator and, of course, the square root of a perfect square is that thing itself.

Example:
\(\displaystyle \sqrt{\frac{a}{b}}=\sqrt{\frac{a}{b}\cdot \frac{b}{b}}=\sqrt{\frac{ab}{b^2}}=\frac{\sqrt{ab}}{b}\).
 
Re: Help Please - Sorry Trying to solve for D

Hi sorry about that - I am trying to solve for D

and I do not under stand how you multiply the top of the fraction by the bottom of the fraction - sorry it has been a long time since I did this
 
You need to solve for D? You don't show a D in your expression. Furthermore, you don't solve expressions. You need to have an equation to solve for an unknown. I think what you need to do, is copy the problem word for word from its source, leaving nothing out. Then we can help you get organized, which is a prerequisite to being successful in math. With regard to "I do not under stand (sic) how you multiply the top of the fraction by the bottom of the fraction" it goes like this.

We know that anything times 1 is that thing itself. We also know that any non-zero number divided by itself is 1. That is, a fraction with the same numerator and denominator is equal to 1. Therefore, given a fraction such as m/n we can do the following...

\(\displaystyle \frac{m}{n}= \frac{m}{n}\cdot 1 = \frac{m}{n}\cdot \frac{n}{n}= \frac{mn}{n^2}\)

Furthermore, you need to start using the language of mathematics if you want to understand what is going on. The "top of a fraction" is called the numerator. The "bottom of a fraction" is the denominator.

If you need more help, please show us your work. We can then, hopefully, identify where you need help.
 
BLH said:
I am not sure if it to be written x=?(R-r)/(R+r) or x=?(R-r)/(R+r) Note: Square root for the entire fraction of R-r/R+r
To learn how to format math as text, please read either of the articles referenced in the "Read Before Posting" thread for this forum. Thank you! :D
 
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