# Solving for a variable fraction, multiplied by a non variable.

• Jun 24th 2010, 11:23 PM
Kaziel
Solving for a variable fraction, multiplied by a non variable.
Okay, so I'm working on through my homework and I get this question:
$\displaystyle I = 1.08\frac{T}{N}$ and I need to solve for N.

The answer is $\displaystyle N = \frac{1.08T}{I}$

Now, I think that one of the first things I want to do is to multiply both sides by N to try and clear the fraction. This is where I get confused. Does it become something like this $\displaystyle NI = (N1.08)T$ or am I not even doing that step correctly?
• Jun 24th 2010, 11:28 PM
p0oint
$\displaystyle NI=1.08T$

You multiplied by N both sides so you will "cut" the N on right side of the equation.

Now divide the equation by I and you will have the answer.

Regards.
• Jun 24th 2010, 11:29 PM
earboth
Quote:

Originally Posted by Kaziel
Okay, so I'm working on through my homework and I get this question:
$\displaystyle I = 1.08\frac{T}{N}$ and I need to solve for N.

The answer is $\displaystyle N = \frac{1.08T}{I}$

Now, I think that one of the first things I want to do is to multiply both sides by N to try and clear the fraction. This is where I get confused. Does it become something like this $\displaystyle NI = (N1.08)T$ or am I not even doing that step correctly?

1. The first step is OK:

$\displaystyle I \cdot N = 1.08\frac{T}{N} \cdot N$

Now cancel the N at the RHS so you don't have any Ns there.

2. Now divide the complete equation by I and you'll get the given result.
• Jun 24th 2010, 11:38 PM
Kaziel
I see what I was doing wrong. I was forgetting that $\displaystyle \frac{x}{y} * \frac{z}{a}$ essentially looks like $\displaystyle \frac{x * z}{y * a}$

With that in mind, an alternate way of writing $\displaystyle I = 1.08\frac{T}{N}$ would be: $\displaystyle I = \frac{1.08}{1}*\frac{T}{N}$ which would make this the same as $\displaystyle I = \frac{1.08T}{N}$. That's easier for me to visualize. I got it now! (Blush) Oi, don't I feel embarrassed...

Thanks for the help folks.(Happy)
• Jun 25th 2010, 07:37 AM
ragnar
As a small note, you may need to justify the fact that you can divide by I on both sides of the equation. In order to do this, you must be sure that I is not zero.