Let the sequence a_1, a_2, a_3, dots, a_{2n} | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(A) Since $a_1, a_2, a_3, \dots, a_{2n}$ form an $A.P.$,the common difference is $d = a_2 - a_1 = a_4 - a_3 = \dots = a_{2n} - a_{2n - 1}$.The given e

Vedclass · Accepted Answer

$\frac{n}{2n - 1}(a_1^2 - a_{2n}^2)$

Vedclass · Answer

(A) Since $a_1, a_2, a_3, \dots, a_{2n}$ form an $A.P.$,the common difference is $d = a_2 - a_1 = a_4 - a_3 = \dots = a_{2n} - a_{2n - 1}$.The given expression is $S = (a_1^2 - a_2^2) + (a_3^2 - a_4^2) + \dots + (a_{2n - 1}^2 - a_{2n}^2)$.Using the identity $x^2 - y^2 = (x - y)(x + y)$,we get:$S = (a_1 - a_2)(a_1 + a_2) + (a_3 - a_4)(a_3 + a_4) + \dots + (a_{2n - 1} - a_{2n})(a_{2n - 1} + a_{2n})$.Since $a_k - a_{k+1} = -d$ for odd $k$,we have:$S = -d(a_1 + a_2 + a_3 + a_4 + \dots + a_{2n - 1} + a_{2n})$.The sum of an $A.P.$ with $2n$ terms is $\frac{2n}{2}(a_1 + a_{2n}) = n(a_1 + a_{2n})$.Thus,$S = -d \cdot n(a_1 + a_{2n})$.From the $A.P.$ formula,$a_{2n} = a_1 + (2n - 1)d$,so $d = \frac{a_{2n} - a_1}{2n - 1}$.Substituting $-d = \frac{a_1 - a_{2n}}{2n - 1}$ into the expression for $S$:$S = \frac{a_1 - a_{2n}}{2n - 1} \cdot n(a_1 + a_{2n}) = \frac{n}{2n - 1}(a_1^2 - a_{2n}^2)$.

Let the sequence $a_1, a_2, a_3, \dots, a_{2n}$ form an $A.P.$ Then $a_1^2 - a_2^2 + a_3^2 - a_4^2 + \dots + a_{2n - 1}^2 - a_{2n}^2 = $

Similar Questions

If $a, b, c$ are in $A.P.$,then $\frac{1}{bc}, \frac{1}{ca}, \frac{1}{ab}$ will be in

The $p^{th}$ term of the series $\left( 3 - \frac{1}{n} \right) + \left( 3 - \frac{2}{n} \right) + \left( 3 - \frac{3}{n} \right) + \dots$ is

Write the first five terms of the sequence whose $n^{th}$ term is $a_{n} = \frac{2n - 3}{6}$.

If the $m^{th}$ terms of the series $63 + 65 + 67 + 69 + \dots$ and $3 + 10 + 17 + 24 + \dots$ are equal,then $m = $

$A$ man starts repaying a loan with a first installment of $Rs. 100$. If he increases the installment by $Rs. 5$ every month,what amount will he pay in the $30^{th}$ installment?

Vedclass Test Series

Exam Paper Generator

Online Exam Module