2015 · Q33
The sum of first 47 terms of the series 1/4+1/5-1/6-1/4-1/5+1/6+1/4+1/5-1/6.... is
Elementary MathematicsAlgebra
- A0
- B-1/6
- C1/6
- D9/20
Explanation
Each block of 6 terms sums to 0; 47 = 7 x 6 + 5, so the sum is just the first 5 terms: 1/4 + 1/5 - 1/6 - 1/4 - 1/5 = -1/6. Hence option (b).