Question 1083476
A1=3/2 , d=1/2
A50=A1+(50-1)×d=3/2+49×(1/2)=1+1/2+49×(1/2)=1+(49+1)×(1/2)=1+50×(1/2)=1+25=26.
A1+A2+A3+....+A50=50×(A1+A50)/2=25×(3/2+26)=25×(3/2+52/2)=25×55/2=1375/2=687.5