A) 3
B) 1
C) 2
D) 3/2
Correct Answer: C
Solution :
\[\frac{1}{1}+\frac{1}{1+2}+\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+\]?? \[{{t}_{n}}=\frac{1}{1+2+3+......n}=\frac{1}{n(n+1)}=2\left[ \frac{1}{n}-\frac{1}{n+1} \right]\] \[\therefore \]Sum \[=S=2\left[ \left( \frac{1}{1}-\frac{1}{2} \right)+\left( \frac{1}{2}-\frac{1}{3} \right)+\left( \frac{1}{3}-\frac{1}{4} \right)+......... \right]\]=2You need to login to perform this action.
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