MEDIUM
JEE Main
IMPORTANT
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Let ann=0 be a sequence such that a0=a1=0 and an+2=3an+1-2an+1,n0.

Then a25a23-2a25a22-2a23a24+4a22a24 is equal to

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Important Questions on Sequences and Series

MEDIUM
JEE Main
IMPORTANT

The number of elements in the set

S=x:2cosx2+x6=4x+4-x is

HARD
JEE Main
IMPORTANT
For three positive integers p, q, r, given xpq2=yqr=zp2r and r=pq+1 such that  3, 3logyx, 3 logzy, 7logxz  are in  A.P. with common difference 12. Then the value of  r-p-q is equal to 
HARD
JEE Main
IMPORTANT
The 4th term of GP is 500 and its common ratio is 1m, mN. Let Sn denote the sum of the first n terms of this GP. If S6>S5+1 and S7<S6+12, then the number of possible values of m is ______
MEDIUM
JEE Main
IMPORTANT
Let the six numbers a1, a2, ..., a6 be in A.P. and a1+a3=10.If the mean of these six numbers is 192 and their variance is σ2, then 8σ2 is equal to
MEDIUM
JEE Main
IMPORTANT
If 13+23+33......upto n terms1·3+2·5+3·7+....upto n terms=95 then the value of n is
HARD
JEE Main
IMPORTANT
Let A1,A2,A3 be the three A.P. with the same common difference d and having their first terms as A,A+1, A+2, respectively. Let a,b,c be the 7th ,9th ,17th  terms of A1, A2, A3, respectively such that a712b171c171+70=0. If a=29, then the sum of first 20 terms of an AP whose first term is c-a-b and common difference is d12, is equal to _____ .
HARD
JEE Main
IMPORTANT
For the two positive numbers a,b, if a,b and 118 are in a geometric progression, while 1a,10 and 1 b are in an arithmetic progression, then, 16a+12b is equal to _____ .