Tentukan rumus suku ke-n dari barisan berikut a. 4, -2, 1, -1/2 b. 2+√3, √3-2, √3-6

4, -2, 1, -1/2
a = 4
r = -1/2
Maka,
[tex]U_n=ar^{n-1} \\ U_n=4(-\frac{1}{2})^{n-1} \\ U_n=4\times(-\frac{1}{2})^{-1}\times (-\frac{1}{2})^n \\ U_n = 4\times -2\times (-2)^{-n} \\ U_n = -8\times(-2)^{-n} \\ U_n = (-2)^3\times(-2)^{-n} \\ U_n = (-2)^{3-n}[/tex]

2.
[tex]2+\sqrt{3},\sqrt{3}-2,\sqrt{3}-6 \\ a=2+\sqrt{3} \\ b=-4 \\ U_n=a+(n-1)b \\ U_n = 2+\sqrt{3}+(n-1)4 \\ U_n = 2+\sqrt{3}+4n-4 \\ U_n = 4n-2+\sqrt{3}[/tex]