Question

Tentukan rumus suku ke -n dari setiap barisan bilangan berikut
a) 2,5,8,11,......
b) 16,32,64,128,......
c) 35,31,27,23,......
d) 108,36,12,4,......

Answer 1

(a) Un = a+(n-1)b
2+(n-1)3
2+3n-3
3n-1

Answer 2

A) Un= a+(n-1)b
= 2+3n-3
=3n-1

b)Un = a x r^n-1
= 16 x 2^n-1
=2^4 x 2^n-1
=2^3+n

c) Un = a+(n-1)b
= 35+(n-1)(-4)
= 35-4n+4
= 39-4n

d) Un = a x r^n-1
= 108 x (1/3)^n-1