If [x] be the greatest integer less than or equal to x, then $$\sum\limits_{n = 8}^{100} {\left[ {{{{{( - 1)}^n}n} \over 2}} \right]} $$ is equal to :
JEE · Math · previous-year question
- A.0
- B.4correct
- C.$$-$$2
- D.2
Answer
B. 4
Explanation
$$\sum\limits_{n = 8}^{100} {\left[ {{{{{( - 1)}^n}n} \over 2}} \right]} $$ = [4] + [-4.5] + [5] + [-5.5] + [6] +..... + [-49.5] + [50] = 4 - 5 + 5 - 6 + 6 ......-50 + 50 = 4
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