SOLUTION: Solve the following: I = E/R + r for r I understand how to do this if there was not a "+ r" in the equation, but I am lost when it comes to the "+ r". I don't know what

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: Solve the following: I = E/R + r for r I understand how to do this if there was not a "+ r" in the equation, but I am lost when it comes to the "+ r". I don't know what       Log On


   

Question 10329: Solve the following:

I = E/R + r for r

I understand how to do this if there was not a "+ r" in the equation, but I am lost when it comes to the "+ r". I don't know what you do with it. I think it would turn into a "1r".

I = E/r, then multiply both sides by r,and end up with the answer: E/I = r?

Please let me know if this is correct, of if I am at least on the right track. Thanks for your help.
Answer by rapaljer(4671) About Me  (Show Source):
You can put this solution on YOUR website!
Do you mean I+=+E%2F%28R+%2B+r%29, solve for r?? If this is what you meant, then you needed parentheses around the (R+r). If that is NOT what you meant, then the solution is quite different from what I am about to do--resubmit the problem, we'll take another look at it. Also, remember that
in math, capital R and lower case r are considered two different variables!

Assuming this is the problem you had in mind:
I%2F1+=+E%2F%28R%2Br%29+. Remember a%2Fb=c%2Fd? It means ad=+bc.

In the same way, I%2F1+=+E%2F%28R%2Br%29+ means that
I%2A%28R%2Br%29+=+1%2AE

Remove parentheses:
IR + Ir = E

Get the small r term all alone on the left side by subtracting IR from each side:
IR - IR + Ir = E - IR
Ir = E-IR

Last, divide both sides by I:
+%28Ir%29%2FI+=+%28E-IR%29%2FI+
+r+=+%28E-IR%29%2FI+

R^2 at SCC