Tentukan rumus suku ke-n barisan bilangan berikut. a. 5, 12, 19, 26, 33,... b. 3, 3/2, 3/4,3/8, c. -2, -8, -18, -32, ... tolong kerjakan pakai cara. makasih
khominghoo
A. 5, 12, 19, 26, 33,... U1 = 5 b = 12-5 = 7 Un = 5 + 7n -7 = 7n -2
b. 3, 3/2, 3/4,3/8,... a = 3 b = (3/2)/3 = 3/6 = ½ Un = 3 x (½)ⁿ-¹
U1 = 5
b = 12-5 = 7
Un = 5 + 7n -7 = 7n -2
b. 3, 3/2, 3/4,3/8,...
a = 3
b = (3/2)/3 = 3/6 = ½
Un = 3 x (½)ⁿ-¹
c. -2, -8, -18, -32, ...
U1 = -2
b1 = -8+2 = -6
b2 = -18+8+6 = -4
2a = -4
a = -4/2 = -2
3a + b = -6
3x(-2) + b = -6
b = -6+6 = 0
a+b+c = -2
c = -2+2+0 = 0
Un = -2n²