1
JEE Main 2021 (Online) 26th August Morning Shift
+4
-1
If the sum of an infinite GP a, ar, ar2, ar3, ....... is 15 and the sum of the squares of its each term is 150, then the sum of ar2, ar4, ar6, ....... is :
A
$${5 \over 2}$$
B
$${1 \over 2}$$
C
$${25 \over 2}$$
D
$${9 \over 2}$$
2
JEE Main 2021 (Online) 25th July Morning Shift
+4
-1
Let Sn be the sum of the first n terms of an arithmetic progression. If S3n = 3S2n, then the value of $${{{S_{4n}}} \over {{S_{2n}}}}$$ is :
A
6
B
4
C
2
D
8
3
JEE Main 2021 (Online) 22th July Evening Shift
+4
-1
Let Sn denote the sum of first n-terms of an arithmetic progression. If S10 = 530, S5 = 140, then S20 $$-$$ S6 is equal to:
A
1862
B
1842
C
1852
D
1872
4
JEE Main 2021 (Online) 20th July Evening Shift
+4
-1
If sum of the first 21 terms of the series $${\log _{{9^{1/2}}}}x + {\log _{{9^{1/3}}}}x + {\log _{{9^{1/4}}}}x + .......$$, where x > 0 is 504, then x is equal to
A
243
B
9
C
7
D
81
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