Question

1. Diketahui barisan aritmatika dengan U1= 3, Un= 87, dan U6 + U7 = 9. Tentukan : a) b=...? b) n=...? c) U50=....?
Pake caraa .. please jawab yaaa:)

Answer 1

U1 = a = 3

U6 + U7 = 9
[a + (6-1)b] + [a + (7-1)b] = 9
[3 + 5b] + [3 + 6b] = 9
6 + 11b = 9
11 b = 9 - 6
11b = 3
b =




Un= 87
a + (n-1)b = 87
3 + (n-1) = 87
3 + - = 87
+ = 87
= 87 -
=
3n = 957
n = 319


U50 = 3 + 49b
       = 3 + 49
       = 3 + 13,3
       = 16,3



semoga membantu :)