tentukan rumus suku ke-n dari masing masing berisan berikut A 5, 7, 9, 11,... B 10,14,18,22,... C 16,21,26,31,.. D 1.000,991,982,973,... E 30,60,90,120,...

A 5, 7, 9, 11,...
a : 5
b : 2
Un = a + ( n-1 ) b
5 + (n - 1) 2
5 + 2n - 2
Un = 2n + 3

B 10,14,18,22,...
a : 10
b : 4
Un= a + ( n-1 ) b
10 + ( n - 1 ) 4
10 + 4n - 4
Un= 4n + 6

C 16,21,26,31,..
a: 16
b: 5
Un= a + (n - 1) b
16 + (n- 1) 5
16 + 5n - 5
Un= 5n + 11

D 1.000,991,982,973,...
a: 1000
b: 9
Un= a + (n-1) b
1000 + (n-1) 9
1000 + 9n-9
Un= 9n + 991

E 30,60,90,120,...
a: 30
b: 30
Un= a + (n-1) b
30+ (n-1) 30
30 + 30n-30
Un= 30n + 0
30n