1. U4 = 3 dan U6 - U1 = 5 2. U6= -5 dan U10-U2 = -2 tentukan suku pertama dan beda nya!

jawab

1)
u4= 3 -->  a+ 3b = 3.... (i)

u6 - u1= 5
a + 5b - a = 5
5b = 5
b = 1 ...(sub ke (i))

a + 3b = 3
a + 3(1) = 3
a= 0

2)
u6 = - 5 --> a + 5b = - 5 ...(i)

u10  - u2 = - 2
(10- 2)b = - 2
8b = -2
b = - 1/4

subke (i)
a + 5b = 5
a + 5(-1/4) = 5
a= 5 + 5/4
a = 25/4