Home
Class 12
MATHS
If a(1),a(2),a(3)(a(1)gt0) are three suc...

If `a_(1),a_(2),a_(3)(a_(1)gt0)` are three successive terms of a GP with common ratio r, the value of r for which `a_(3)gt4a_(2)-3a_(1)` holds is given by

A

`1ltrlt3`

B

`-3ltrlt-1`

C

`rlt1` or `rgt3`

D

None of these

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the value of the common ratio \( r \) for which the inequality \( a_3 > 4a_2 - 3a_1 \) holds, given that \( a_1, a_2, a_3 \) are three successive terms of a geometric progression (GP). ### Step-by-Step Solution: 1. **Define the terms of the GP**: Let \( a_1 = a \), \( a_2 = ar \), and \( a_3 = ar^2 \), where \( a > 0 \) and \( r \) is the common ratio. 2. **Set up the inequality**: We need to analyze the inequality: \[ a_3 > 4a_2 - 3a_1 \] Substituting the terms of the GP into the inequality, we have: \[ ar^2 > 4(ar) - 3a \] 3. **Simplify the inequality**: Rearranging the terms gives: \[ ar^2 > 4ar - 3a \] Dividing through by \( a \) (since \( a > 0 \)): \[ r^2 > 4r - 3 \] 4. **Rearrange into standard quadratic form**: Rearranging the above inequality results in: \[ r^2 - 4r + 3 > 0 \] 5. **Factor the quadratic**: The quadratic \( r^2 - 4r + 3 \) can be factored as: \[ (r - 1)(r - 3) > 0 \] 6. **Determine the intervals**: To solve the inequality \( (r - 1)(r - 3) > 0 \), we find the critical points, which are \( r = 1 \) and \( r = 3 \). We can use the test point method or the wavy curve method to determine the sign of the expression in the intervals defined by these points: - For \( r < 1 \): Choose \( r = 0 \) → \( (0 - 1)(0 - 3) = 3 > 0 \) (positive) - For \( 1 < r < 3 \): Choose \( r = 2 \) → \( (2 - 1)(2 - 3) = -1 < 0 \) (negative) - For \( r > 3 \): Choose \( r = 4 \) → \( (4 - 1)(4 - 3) = 3 > 0 \) (positive) 7. **Combine the intervals**: The solution to the inequality \( (r - 1)(r - 3) > 0 \) is: \[ r < 1 \quad \text{or} \quad r > 3 \] ### Final Answer: Thus, the values of \( r \) for which the inequality holds are: \[ r \in (-\infty, 1) \cup (3, \infty) \]
Promotional Banner

Topper's Solved these Questions

  • SEQUENCES AND SERIES

    ARIHANT MATHS ENGLISH|Exercise Exercise For Session 4|10 Videos
  • SEQUENCES AND SERIES

    ARIHANT MATHS ENGLISH|Exercise Exercise For Session 5|8 Videos
  • SEQUENCES AND SERIES

    ARIHANT MATHS ENGLISH|Exercise Exercise For Session 2|11 Videos
  • PROPERTIES AND SOLUTION OF TRIANGLES

    ARIHANT MATHS ENGLISH|Exercise Exercise (Questions Asked In Previous 13 Years Exam)|21 Videos
  • SETS, RELATIONS AND FUNCTIONS

    ARIHANT MATHS ENGLISH|Exercise Exercise (Questions Asked In Previous 13 Years Exam)|12 Videos

Similar Questions

Explore conceptually related problems

If a_(1), a_(2), a_(3)(a_(1)gt 0) are in G.P. with common ratio r, then the value of r, for which the inequality 9a_(1)+5 a_(3)gt 14 a_(2) holds, can not lie in the interval

Let a_(1),a_(2),a_(3) , be three positive numbers which are G.P. with common ratio r. The inequality a_(3) gt a_(2) + 2a_(1) do not holds if r is equal to

If a_(1), a_(2), a_(3), a_(4), a_(5) are consecutive terms of an arithmetic progression with common difference 3, then the value of |(a_(3)^(2),a_(2),a_(1)),(a_(4)^(2),a_(3),a_(2)),(a_(5)^(2),a_(4),a_(3))| is

If a_(1),a_(2),a_(3),a_(4) and a_(5) are in AP with common difference ne 0, find the value of sum_(i=1)^(5)a_(i) " when " a_(3)=2 .

a_(1),a_(2),a_(3),a_(4),a_(5), are first five terms of an A.P. such that a_(1) +a_(3) +a_(5) = -12 and a_(1) .a_(2) . a_(3) =8 . Find the first term and the common difference.

Given that a_(4)+a_(8)+a_(12)+a_(16)=224 , the sum of the first nineteen terms of the arithmetic progression a_(1),a_(2),a_(3),…. is equal to

If a_(1),a_(2),a_(3),"….",a_(n) are in AP, where a_(i)gt0 for all I, the value of (1)/(sqrta_(1)+sqrta_(2))+(1)/(sqrta_(2)+sqrta_(3))+"....."+(1)/(sqrta_(n-1)+sqrta_(n)) is

If a_(1),a_(2),a_(3),"........" is an arithmetic progression with common difference 1 and a_(1)+a_(2)+a_(3)+"..."+a_(98)=137 , then find the value of a_(2)+a_(4)+a_(6)+"..."+a_(98) .

If a_(1), a_(2), a_(3) are in arithmetic progression and d is the common diference, then tan^(-1)((d)/(1+a_(1)a_(2)))+tan^(-1)((d)/(1+a_(2)a_(3)))=

If a_(0), a_(1), a_(2),… are the coefficients in the expansion of (1 + x + x^(2))^(n) in ascending powers of x, prove that a_(0) a_(2) - a_(1) a_(3) + a_(2) a_(4) - …+ a_(2n-2) a_(2n)= a_(n+1) .