A) U3=15 dan b=2,tentukan u1 dan u12 B) U4=33 dan b=5,tentukan u1 dan u10 C) U5=20 dan b=-1, tentukan u1 dan u15

Rumus Un = a + (n - 1)b

A) U3 = 15 ---> a + 2b = 15, b=2
a + 2(2) = 15
a + 4 = 15
a = 15 - 4
a = 11
U1 = a = 11
U12 = a + 11b = 11 + 11(2) = 11 + 22 = 33

B) U4 = 33 ---> a + 3b = 33, b = 5
a + 3(5) = 33
a + 15 = 33
a = 33 - 15
a = 18
U1 = a = 18
U10 = a + 9b = 18 + 9(5) = 18 + 45 = 63

C) U5 = 20 ---> a + 4b = 20, b = -1
a + 4(-1) = 20
a - 4 = 20
a = 20 + 4
a = 24
U1 = a = 24
U15 = a + 14b = 24 + 14(-1) = 24 - 14 = 10