Jawabanmu

2014-01-09T14:39:17+07:00
Un = a + (n-1)b
61 = 4 + (n-1)3
61 = 4 +3n - 3
3n = 61 - 1
3n = 60
n = 20
2 4 2
2014-01-09T14:46:33+07:00
Un=a+(n-1)b
61=4+(n-1)3
61=4+3n-3
61=4-3+3n
61=1+3n
61-1=3n
60=3n
20=n