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January 30, 2015

January 30, 2015

Posted by **Jon** on Sunday, December 6, 2009 at 9:49pm.

The total electrical resistance R of two resistors connected in parallel with resistances R1 and R2 is given by 1/R=1/R1+1/R2. One resistor has a resistance of 2.3 ohms. Let x be the resistance of the second resistor. Find the resistance of the second resistor if the total resistance of the pair is 1.7 ohms.

I'm not sure how to go about this I thought maybe:

1/1.7=1/2.3+1/x

I've never done anything like this before

- Pre-Calc -
**Reiny**, Sunday, December 6, 2009 at 9:55pmOk so far

Don't let the fractions scare you

1/1.7 - 1/2.3 = 1/x

.15345 = 1/x , take reciprocal of both sides, (flip it)

1/.15345 = x/1

x = 6.5

check: 1/2.3 + 1/6.5 = .5886

1/1.7 = .2882 (close enough)

- Pre-Calc -
**Jon**, Sunday, December 6, 2009 at 9:59pmOk, thanks. That's actually what I have in my notebook. I just wasn't sure if I was going about it right.

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