HARD
JEE Main
IMPORTANT
Earn 100

Let the sum of the first three terms of an A.P. be 39 and the sum of its last four terms be 178. If the first term of this A.P. is 10, then the median of the A.P. is :

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Important Questions on Sequences and Series

HARD
JEE Main
IMPORTANT
The sum of first 9 terms of the series 131+13+231+3+13+23+331+3+5+... is
HARD
JEE Main
IMPORTANT

If m is the A.M. of two distinct real numbers I and n I, n>1  and G1, G2 and G3 are three geometric means between I and n, then G14+2G24+G34 equals

MEDIUM
JEE Main
IMPORTANT
The sum of the 3rd and the 4th terms of a G.P. is 60 and the product of its first three terms is 1000. If the first term of this G.P. is positive, then its 7th term is:
HARD
JEE Main
IMPORTANT
If n=1 5 1nn+1n+2n+3=k3,  then k is equal to:
HARD
JEE Main
IMPORTANT
Let fn=13+3n100n, where [n] denotes the greatest integer less than or equal to n. Then n=156fn is equal to
HARD
JEE Main
IMPORTANT
The number of terms in an A.P. is even, the sum of the odd terms in it is 24 and that the even terms is 30. If the last term exceeds the first term by 1012, then the number of terms in the A.P. is 
HARD
JEE Main
IMPORTANT
Given an A.P. whose terms are all positive integers. The sum of its first nine terms is greater than 200 and less than 220.  If the second term in it is 12, then its 4th term is :
HARD
JEE Main
IMPORTANT
If the sum 312+512+22+712+22+32+.....+ up to 20 terms is equal to k21, then k is equal to