JEE Advanced · Mathematics · 5. Sequences & Series
Let for Suppose are in Arithmetic Progression (A.P.) with the common difference Suppose are in A.P. such that and If and then
- A
- B
- C
- D
Answer & Solution
Correct Answer
(B)
Step-by-step Solution
Detailed explanation
If \(\log _e b_1, \log _e b_2 \ldots . \log _e b_{101} \rightarrow A P ; \quad\) difference \(( d )=\log _e 2\)
Let Common Difference = D
Given, and
\( \Rightarrow a_1+50 D=2^{50} b_1 \)
\( \therefore a_1+50 D=2^{50} a_1\left(A s b_1=a_1\right) \Rightarrow\) \(D=\frac{2^{50} a_1-a_1}{50} \)
\( t=b_1+b_2+\ldots \ldots b_{51}=b_1+2 b_1\) \(+~2^2 b_1+\ldots \ldots 2^{50} b_1 \Rightarrow t=b_1\left(2^{51}-1\right) ; \)
\( s=a_1+a_2+\ldots \ldots a_{51} \Rightarrow s=\frac{51}{2}(2a_1\) \(+~50 D) \)
\( t=a_1 \cdot 2^{51}-a_1 \Rightarrow t1 \text { \& } a_1=b_1\) so \(a_1>1) \)
\( s=\frac{51}{2}\left(a_1+a_1+50 D\right) \)
\( s=\frac{51}{2}\left(a_1+2^{50} a_1\right) \)
\( s=\frac{51 a_1}{2}+\frac{51}{2} \cdot 2^{50} a_1 \)
\( \Rightarrow s>a_1 \cdot 2^{51} \ldots \ldots \text { (ii) }\)
Clearly (from equation (i) and (ii))
Also
\(\therefore a_{101}=a_1+100\left(\frac{2^{50} a_1-a_1}{50}\right) ; b_{101}\) \(=2^{100} a_1 \ldots \ldots \text { (ii) }\)
\(a_{101}=a_1+2^{51} a_1-2 a_1 \Rightarrow a_{101}=\) \(2^{51} a_1-a_1 \Rightarrow a_{101}<2^{51} a_1 \ldots \ldots .( iv )\)
Clearly (from equation (iii) and (iv))
Let Common Difference = D
Given, and
\( \Rightarrow a_1+50 D=2^{50} b_1 \)
\( \therefore a_1+50 D=2^{50} a_1\left(A s b_1=a_1\right) \Rightarrow\) \(D=\frac{2^{50} a_1-a_1}{50} \)
\( t=b_1+b_2+\ldots \ldots b_{51}=b_1+2 b_1\) \(+~2^2 b_1+\ldots \ldots 2^{50} b_1 \Rightarrow t=b_1\left(2^{51}-1\right) ; \)
\( s=a_1+a_2+\ldots \ldots a_{51} \Rightarrow s=\frac{51}{2}(2a_1\) \(+~50 D) \)
\( t=a_1 \cdot 2^{51}-a_1 \Rightarrow t1 \text { \& } a_1=b_1\) so \(a_1>1) \)
\( s=\frac{51}{2}\left(a_1+a_1+50 D\right) \)
\( s=\frac{51}{2}\left(a_1+2^{50} a_1\right) \)
\( s=\frac{51 a_1}{2}+\frac{51}{2} \cdot 2^{50} a_1 \)
\( \Rightarrow s>a_1 \cdot 2^{51} \ldots \ldots \text { (ii) }\)
Clearly (from equation (i) and (ii))
Also
\(\therefore a_{101}=a_1+100\left(\frac{2^{50} a_1-a_1}{50}\right) ; b_{101}\) \(=2^{100} a_1 \ldots \ldots \text { (ii) }\)
\(a_{101}=a_1+2^{51} a_1-2 a_1 \Rightarrow a_{101}=\) \(2^{51} a_1-a_1 \Rightarrow a_{101}<2^{51} a_1 \ldots \ldots .( iv )\)
Clearly (from equation (iii) and (iv))
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Mathematics
- In a non-right-angled triangle let denote the lengths of the sides opposite to the angles at respectively. The median from meets the side at the perpendicular from meets the side at , and and intersect at If and the radius of the circumcircle of the equals then which of the following options is/are correct?JEE Advanced 2019 Hard
- Let and be functions defined by
(i)
(ii) , where the inverse trigonometric function assumes values in
(iii) , where, for denotes the greatest integer less than or equal to ,
(iv)
The correct option is :LIST-I LIST-II A. the function is P. NOT continuous at B. The function is Q. continuous at and NOT differentiable at C. The function is R. differentiable at and its derivative is NOT continuous at D. The function is S. differentiable at and its derivative is continuous at JEE Advanced 2018 Medium - Consider the lines given by
\[
L_1: x+3 y-5=0, L_2: 3 x-k y-1=0, L_3: 5 x+2 y-12=0
\]
Match the Statements/Expressions in Column I with the Statements/Expressions in Column II.
JEE Advanced 2008 Medium - Let be a differentiable function such that and If , for thenJEE Advanced 2017 Medium
- Let denote the digit number where the first and the last digits are and the remaining digits are . Consider the sum . If , where and are natural numbers less than , then the value of isJEE Advanced 2023 Hard
- Let be a natural number and be the function defined by
If is such that the area of the region bounded by the curves and is , then the maximum value of the function isJEE Advanced 2023 Medium
More PYQs from JEE Advanced
- For diatomic molecules, the correct statement(s) about the molecular orbitals formed by the overlap of two orbitals is(are)JEE Advanced 2022 Medium
- Paragraph :
Two plane harmonic sound waves are expressed by the equations.
\(
\begin{aligned}
& y_1(x, t)=A \cos (0.5 \pi x-100 \pi t) \\
& y_2(x, t)=A \cos (0.46 \pi x-92 \pi t)
\end{aligned}
\)
(All parameters are in MKS)
Question :
What is the speed of the sound?JEE Advanced 2006 Easy - Airplanes A and B are flying with constant velocity in the same vertical plane at angles and with respect to the horizontal respectively as shown in the figure. The speed of A is . At time t = 0 s, an observer in A finds B at a distance of 500 m. This observer sees B moving with a constant velocity perpendicular to the line of motion of A. If at , A just escapes being hit by B, t0 in seconds is
JEE Advanced 2014 Hard - In a radioactive decay chain, nucleus decays to nucleus. Let be the number of particles, respectively, emitted in this decay process. Which of the following statements is (are) true?JEE Advanced 2018 Medium
- Let be the origin and and for some If then which of the following statements is (are) TRUE?JEE Advanced 2021 Medium
- The equilibrium \(2 \mathrm{Cu}^{\mathrm{I}} \rightleftharpoons \mathrm{Cu}^0+\mathrm{Cu}^{\text {II }}\) in aqueous medium at \(25^{\circ} \mathrm{C}\) shifts towards the left in the presence ofJEE Advanced 2011 Hard