SOLUTION: Hi there, I'm trying to solve R=(R1xR2)/(R1+R2) for R2 and can't seem to wrap my brain around it. Any help would be greatly appreciated. Thanks!

Algebra ->  Equations -> SOLUTION: Hi there, I'm trying to solve R=(R1xR2)/(R1+R2) for R2 and can't seem to wrap my brain around it. Any help would be greatly appreciated. Thanks!      Log On


   



Question 814760: Hi there, I'm trying to solve R=(R1xR2)/(R1+R2) for R2 and can't seem to wrap my brain around it. Any help would be greatly appreciated. Thanks!
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
What you have is the rule for finding the
equivalent resistor, +R+, for 2 resistors
+R%5B1%5D+ and +R%5B2%5D+ in parallel.
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+R+=+%28+R%5B1%5D%2AR%5B2%5D+%29+%2F+%28+R%5B1%5D+%2B+R%5B2%5D+%29+
Multiply both sides by +R%5B1%5D+%2B+R%5B2%5D+
+R%2A%28+R%5B1%5D+%2B+R%5B2%5D+%29+=+R%5B1%5D%2AR%5B2%5D+
+R%2AR%5B1%5D+%2B+R%2AR%5B2%5D+=+R%5B1%5D%2AR%5B2%5D+
Subtract +R%2AR%5B2%5D+ from both sides
+R%2AR%5B1%5D+=+R%5B1%5D%2AR%5B2%5D+-+R%2AR%5B2%5D+
+R%2AR%5B1%5D+=+R%282%29%2A%28+R%5B1%5D+-+R+%29+
Divide both sides by +R%5B1%5D+-+R+
+R%5B2%5D+=+%28+R%2AR%5B1%5D+%29+%2F+%28+R%5B1%5D+-+R+%29+
Divide top and bottom of the right side by +R%5B1%5D+
+R%5B2%5D+=+R+%2F+%28%28+1+-+%28R%2FR%5B1%5D%29+%29%29+ answer
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check the answer:
+R+=+%28+R%5B1%5D%2AR%5B2%5D+%29+%2F+%28+R%5B1%5D+%2B+R%5B2%5D+%29+
Let +R%5B1%5D+=+4+
Let +R%5B2%5D+=+16+
+R+=+%28+4%2A16+%29+%2F+%28+4+%2B+16+%29+
+R+=+64%2F20+
+R+=+3.2+
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+R%5B2%5D+=+R+%2F+%28%28+1+-+%28R%2FR%5B1%5D%29+%29%29+
+R%5B2%5D+=+3.2+%2F+%28+1+-+3.2%2F4+%29+
+R%5B2%5D+=+3.2+%2F+%28+1+-+3.2%2F4+%29+
+R%5B2%5D+=+3.2+%2F+%28+1+-+.8+%29+
+R%5B2%5D+=+3.2+%2F+.2+
+R%5B2%5D+=+16+
OK