Diketahui suatu barisan 4,7,10,13,… tentukan suku ke 15

U1=a=4
U2 = a+b=7
b = u2-u1 = 7-4 = 3
u15 = a+14b
u15 = 4 + 14(3) = 46

A=4
B=7-4=3
Un= a+(n-1) b
= 4+(n-1) 3
= 4+3n-3
= 3n+1
U15= 3(15) +1
= 45+1
= 46