Last Updated on May 4, 2023
We are given the reciprocal of r is equal to the sum of the reciprocals of x and y. Thus we can say:
1/r = 1/x + 1/y
Getting a common denominator for the right side of the equation we have:
1/r = y/xy + x/xy
1/r = (y + x)/xy
If we reciprocate both sides of the equation, we have:
r = xy/(y+x)
Answer: D
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