Question 355152
n/2(a[1]+a[n])=S[n]
n/2 * (3+136)=1390
n/2 * 139 = 1390
278n=2780 Multiply each side by 2.
n=10
.
136-3=133
133/9 common difference=d
.
c=a[1]-d
c= 3 - 133/9 = -106/9
a[n]=dn+c
a[2]= 133/9 * 2 -106/9 = 160/9
.
a[3]= 133/9 * 3 -106/9 = 293/9
.
Ed