EASY
JEE Main
IMPORTANT
Earn 100

Let 116,a and b be in G.P. and 1a,1 b,6 be in A.P., where a,b>0. Then 72(a+b) is equal to _______ .

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Important Questions on Sequences and Series

HARD
JEE Main
IMPORTANT
Let Sn(x)=loga1/2x+loga1/3x+loga1/6x+loga1/11x+loga1/18x+loga1/27x+ up to n-terms, where a>1. If S24(x)=1093 and S12(2x)=265, then value of a is equal to _____ .
MEDIUM
JEE Main
IMPORTANT
If 1,log104x-2 and log104x+185 are in arithmetic progression for a real number x then the value of the determinant 2x-12x-1x210xx10 is equal to:
MEDIUM
JEE Main
IMPORTANT
If α, β are natural numbers such that 100α-199β=(100)(100)+(99)(101)+(98)(102)+..+(1)(199), then the slope of the line passing through (α, β) and origin is:
EASY
JEE Main
IMPORTANT
Let S1 be the sum of first 2n terms of an arithmetic progression. Let S2 be the sum of first 4n terms of the same arithmetic progression. If S2-S1 is 1000, then the sum of the first 6n terms of the arithmetic progression is equal to:
HARD
JEE Main
IMPORTANT
If ecos2x+cos4x+cos6x+....loge2 satisfies the equation t2-9t+8=0, then the value of 2sinxsinx+3cosx, where 0<x<π2, is equal to
MEDIUM
JEE Main
IMPORTANT
The sum of first four terms of a geometric progression G.P. is 6512 and the sum of their respective reciprocals is 6518. If the product of first three terms of the G.P. is 1, and the third term is α, then 2α is _________.
MEDIUM
JEE Main
IMPORTANT
If 0<θ,ϕ<π2,x=n=0cos2nθ,y=n=0sin2nϕ and z=n=0cos2nθ·sin2nϕ then :