SOLUTION: hi my problem is this. 1/f=1/s+1/r (solve for s) please show all steps so i can understand how to work similar problems

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Question 11848: hi my problem is this. 1/f=1/s+1/r (solve for s) please show all steps so i
can understand how to work similar problems
Answer by rapaljer(4671) About Me  (Show Source):
You can put this solution on YOUR website!
1%2Ff=1%2Fs%2B1%2Fr

Begin by finding the LCD for the entire problem, which is fsr.

Multiply both sides of the equation by fsr:
+%28fsr%29%2A%281%2Ff%29+=+%28fsr%29%2A%281%2Fs%29+%2B+%28fsr%29%2A%28+1%2Fr%29

In the first fraction, the f divides out,
in the second, the s divides out, and
in the third fraction, the r divides out.

What is left will be:
sr+=+fr+%2B+fs

You are solving for s, so get the s terms all on the left side by subtracting fs from each side:
sr+-+fs+=+fr+%2B+fs+-+fs
sr+-+fs+=+fr

Get the s in one place by factoring out the s:
s%28r-f%29+=+fr

Last, divide both sides by (r-f):

+%28s%2A%28r-f%29%29%2F%28r-f%29+=+%28f%2Ar%29%2F%28r-f%29+

Final answer:
+s+=+%28f%2Ar%29%2F%28r-f%29+

R^2 at SCC