a9 = a1+ 8d = 14
2 + 8d = 14
8d = 12
d = 12/8 = 6/4 = 3/2
a5 = a1 + 4d
a5 = 2 + 4*3/2
a5 = 8
S = (a5+a9)*5/2 = (8+14)*5/2 = 11*5 = 55
a₁=2
a₉=a₁+8d=14
2+8d=14
8d=12
d=1,5
a₅=a₁+4d
a₅=2+4*1,5=8
S₅=(a₅+a₉)*5/2=(8+14)*5/2=11*5=55
a9 = a1+ 8d = 14
2 + 8d = 14
8d = 12
d = 12/8 = 6/4 = 3/2
a5 = a1 + 4d
a5 = 2 + 4*3/2
a5 = 8
S = (a5+a9)*5/2 = (8+14)*5/2 = 11*5 = 55
a₁=2
a₉=a₁+8d=14
2+8d=14
8d=12
d=1,5
a₅=a₁+4d
a₅=2+4*1,5=8
S₅=(a₅+a₉)*5/2=(8+14)*5/2=11*5=55