Question

find the sum of 3/sqrt.5 ,sqrt.5,7/sqrt.5 for 15 term

Answer 1

a=3/√5. d=2/√5. n=15. Sn=?
Sn=(n/2)[2a+(n-1)d]
S15=15/2{(6/√5)+14*2/√5}
=15/2{(6/√5)+28/√5}
=15/2{34/√5}
=255/√5