tentukan pola bilangan ke n dari barisan 3,5,7,9,11,...

3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41......

》3, 5, 7, 9, 11

U1 = a = 3
U2 = a+b = 5
U3 = a+2b = 7
U4 = a+3b = 9

Beda(b) :
U2 = a+b = 5
U3 = a+2b = 7
-------------- -
》 -b = -2
》 b = 2

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

Semoga membantu.. ^_^