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If a, b, c are three unequal numbers such that a,b,c are in AP. and b - a, c - b, a are in GP., then the ratio
a : b : c is equal.

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Important Questions on Arithmetic and Geometric Progression

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Let C0 be a circle of radius 1. For n1, let Cn be a circle whose area equals the area of a square inscribed in Cn-1. Then u=0areaCi equals,
MEDIUM
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

Let S1 be the sum of areas of the squares whose sides are parallel to coordinate axes. Let S2 be the sum of areas of the slanted squares as shown in the figure. Then S1/S2 is

Question Image

MEDIUM
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:
EASY
Let a1,a2,..a10 be a G.P. If a3a1=25, then a9a5  equals:
 
MEDIUM
If three distinct numbers a, b, c are in G.P. and the equations ax2+2bx+c=0 and dx2+2ex+f=0 have a common root, then which one of the following statements is correct?
MEDIUM
The quotient when 1+x2+x4+...+x34 is divided by 1+x+x2+...+x17 is
MEDIUM
The greatest positive integer k, for which 49k+1 is a factor of the sum 49125+49124++492+49+1, is
EASY
The product of three consecutive terms of a G.P. is 512. If 4 is added to each of the first and the second of these terms, the three terms now form an A.P., then the sum of the original three terms of the given G.P. is :
HARD
The number of real solutions of the equation sin-1i=1xi+1-xi=1x2i=π2-cos-1i=1 -x2i-i=1-xi lying in the interval -12,12 is____.

(Here, the inverse trigonometric functions sin-1x & cos-1x assume values in -π2,π2 & 0,π

respectively.)
MEDIUM
Let a, b and c be in G.P. with common ratio r, where a0 and 0<r12. If 3a, 7b and 15c are the first three terms of an A.P., then the 4th term of this A.P. is :
HARD

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
If α,β and γ are three consecutive terms of a non-constant G.P. Such that the equations αx2+2βx+γ=0 and x2+x-1=0 have a common root, then αβ+γ is equal to:
MEDIUM
If the 2nd, 5th and 9th terms of a non-constant arithmetic progression are in geometric progression, then the common ratio of this geometric progression is
EASY
If the sum of an infinite GP be 9 and sum of first two terms be 5 then their common ratio is …..
MEDIUM
If x=n=0-1ntan2nθ and y=n=0cos2nθ, for 0<θ<π4, then:
EASY
The product 214·4116·8148·161128·.... to is equal to:
MEDIUM
The sum of first 20 terms of the sequence 0.7, 0.77, 0.777, ......, is :
HARD
Let bi>1 for i=1, 2,.,101. Suppose logeb1,logeb2,..,logeb101 are in Arithmetic Progression (A.P.) with the common difference loge2.  Suppose a1, a2,.,a101 are in A.P. such that a1=b1 and a51=b51. If t=b1+b2++b51 and s=a1+a2++a51, then
EASY
If a1x=b1y=c1z and a, b, c are in G.P., then x, y, z  will be in