Diberikan barisan 7,11,20,34 tentukanlah suku ke 23.....

7, 11, 20 ,34, ....
B1 = 4,9,14
B2 = 5 , 5
2a = 5
a = 5/2
3a + b = 4
3(5/2) + b = 4
15/2 + b = 8/2
b = -7/2

a+b+c = 7
5/2-7/2 + c = 14/2
c = 14/2 + 2/2
c = 8

Un = (5n² -7n)/2 + 8
U23 = (5x23² - 7x23)/2 + 8
= (5 x529 - 161)/2 + 8
= (2.645 - 161)/2 + 8
= 2.484/2 + 8
= 1.242 + 8
= 1.250