Question

Find the sum of the series

5+(-41)+9+(-39)+13+(-37)+17+.......+(-5)+81+(-3

Answer 1

5+9+13.....81 n=(81-5)/4=19

sn 1 = 19×43

-41 -39 -3 n=(-41-(-3))/2=19

sn 2= 19×-22

sn = sn 1+ sn2

= ...... ans