1
JEE Main 2019 (Online) 9th January Morning Slot
+4
-1
Let $${a_1},{a_2},.......,{a_{30}}$$ be an A.P.,

$$S = \sum\limits_{i = 1}^{30} {{a_i}}$$ and $$T = \sum\limits_{i = 1}^{15} {{a_{\left( {2i - 1} \right)}}}$$.

If $$a_5$$ = 27 and S - 2T = 75, then $$a_{10}$$ is equal to :
A
47
B
42
C
52
D
57
2
JEE Main 2018 (Online) 16th April Morning Slot
+4
-1
Out of Syllabus
The sum of the first 20 terms of the series

$$1 + {3 \over 2} + {7 \over 4} + {{15} \over 8} + {{31} \over {16}} + ...,$$ is :
A
$$38 + {1 \over {{2^{19}}}}$$
B
$$38 + {1 \over {{2^{20}}}}$$
C
$$39 + {1 \over {{2^{20}}}}$$
D
$$39 + {1 \over {{2^{19}}}}$$
3
JEE Main 2018 (Online) 16th April Morning Slot
+4
-1
Let $${1 \over {{x_1}}},{1 \over {{x_2}}},...,{1 \over {{x_n}}}\,\,$$ (xi $$\ne$$ 0 for i = 1, 2, ..., n) be in A.P. such that x1=4 and x21 = 20. If n is the least positive integer for which $${x_n} > 50,$$ then $$\sum\limits_{i = 1}^n {\left( {{1 \over {{x_i}}}} \right)}$$ is equal to :
A
$${1 \over 8}$$
B
3
C
$${{13} \over 8}$$
D
$${{13} \over 4}$$
4
JEE Main 2018 (Offline)
+4
-1
Out of Syllabus
Let A be the sum of the first 20 terms and B be the sum of the first 40 terms of the series
12 + 2.22 + 32 + 2.42 + 52 + 2.62 ...........
If B - 2A = 100$$\lambda$$, then $$\lambda$$ is equal to
A
496
B
232
C
248
D
464
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