MEDIUM
JEE Main
IMPORTANT
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Let the sum of the first n terms of a non-constant A.P., a1, a2, a3, ...., an be 50n+n(n-7)2A, where A is a constant. If d is the common difference of this A.P., then the ordered pair d, a50 is equal to

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Important Questions on Sequences and Series

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JEE Main
IMPORTANT
The sum of the series 1+2×3+3×5+4×7+ upto 11th term is:
MEDIUM
JEE Main
IMPORTANT
Some identical balls are arranged in rows to form an equilateral triangle. The first row consists of one ball, the second row consists of two balls and so on. If 99 more identical balls are added to the total number of balls used in forming the equilateral triangle, then all these balls can be arranged in a square, whose each side contains exactly 2 balls less than the number of balls each side of the triangle contains. Then the number of balls used to form the equilateral triangle is
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JEE Main
IMPORTANT
If the sum and product of the first three terms in an A.P. are 33 and 1155, respectively, then a value of its 11th term is:
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JEE Main
IMPORTANT
If a, b and c be three distinct real numbers in G.P. and a+b+c=xb, then x cannot be:
HARD
JEE Main
IMPORTANT
Let a1, a2, , a30 be an A.P., S= i=130ai and T= i=115a(2i-1). If a5=27 and S-2T=75, then a10 is equal to:
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JEE Main
IMPORTANT
The sum of the following series 1+6+912+22+327+1212+22+32+429+15(12+22++52)11+.... up to 15 terms, is:
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JEE Main
IMPORTANT
Let a, b and c be the 7th, 11th and 13th terms respectively of a non-constant A.P. If these are also the three consecutive terms of a G.P., then ac is equal to:
HARD
JEE Main
IMPORTANT
The sum of all natural numbers n such that 100<n<200 and H.C.F. 91,n>1 is