If-a-1-a-2-a-3-be-an-AP-then-prove-that-n-1-2m-1-n-1-a-n-2-m-2m-1-a-n-2-a-2m-2-

Question Number 108553 by I want to learn more last updated on 17/Aug/20

If a_{1}, a_{2}, a_{3}, be an AP, then prove that :

\underset{n = 1}{\sum^{2 m}} {(- 1)}^{n - 1} a_{n}^{2} = \frac{m}{2 m - 1} (a_{n}^{2} - a_{2 m}^{2})