Question

plz me ans fast confused

Answer 1

hi!

here is your answer

The steps are given in the pic.


so,

$sm + n = \\ \frac{m + n}{2} (2a + (m + n - 1)d)$


hence , from (1)

$sm + n = \frac{m + n}{2} (0)....from1$


$sm + n = 0$

$hence \: proved$

Answer 2

I will answer you tomorrow it is too late now