Divide 50 into two parts, such that the sum of their reciprocals is 1/12.
2025
Divide 50 into two parts, such that the sum of their reciprocals is 1/12.
- A.
25, 25
- B.
10, 40
- C.
20, 30
- D.
20,40
Attempted by 255 students.
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Correct answer: C
Let the two parts be x and 50 − x.
Given that the sum of their reciprocals is 1/12:
1/x + 1/(50 − x) = 1/12.
Combine the fractions:
(50 − x + x) / [x(50 − x)] = 1/12
50 / [x(50 − x)] = 1/12
So x(50 − x) = 600.
Expand and rearrange:
50x − x² = 600 ⇒ x² − 50x + 600 = 0.
Solve the quadratic:
x = [50 ± √(2500 − 2400)]/2 = [50 ± 10]/2.
Thus x = 20 or x = 30, giving the two parts as 20 and 30.