***I will give you a medal***
If R is the total resistance for a parallel circuit with two resistors of resistance r1 and r2, then . Find the resistance, r1, if the total resistance R is 20 ohms, and r2 is 75 ohms. Round your answer to the nearest ohm if necessary.
1/R = 1/r1+1/r2
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OpenStudy (anonymous):
@jim_thompson5910
jimthompson5910 (jim_thompson5910):
1/R = 1/r1 + 1/r2
1/20 = 1/x + 1/75
solve for x
OpenStudy (anonymous):
its going to be a negative 55
jimthompson5910 (jim_thompson5910):
no
OpenStudy (anonymous):
idk then
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jimthompson5910 (jim_thompson5910):
the LCD is 150x, multiply each fraction by the LCD to clear out the fractions
OpenStudy (anonymous):
i get 7.5 = 150/r1 + 2
jimthompson5910 (jim_thompson5910):
oh sry, i miscalculated the LCD
the LCD is actually 300x
300x times 1/20 = 15x
300x times 1/x = 300
300x times 1/75 = 4x
jimthompson5910 (jim_thompson5910):
so
1/20 = 1/x + 1/75
is the same as
15x = 300 + 4x
jimthompson5910 (jim_thompson5910):
now solve 15x = 300 + 4x for x
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