Question

Find the sum of the series 5+7+9+11+13.... Upto 40 terms

Answer 1

here
first term a=5
last term l=83
d=2
n=40
n/2(a+l)=1760

Answer 2

#Hey mate#
a=5
d=2
n=40
Sol:
Sn=n/2[2a+(n-1)d]
    =40/2[2×5+(40-1)2]
    =20[10+39×2]
    =20[10+78]
    =20×88
Sn=1760



#$amu#