1. tentukan rumus suku ke -n dan suku ke - 8 barisan di bawah a) 4,-8,16,-32 b) 1/2 ,1/4 ,1/8

a) 4,-8,16,-32
a = 4
r = -8/4 = -2
Un = 4 x (-2)ⁿ-¹
U8 = 4 x (-2)^8-1 = 4 x -2^7 = -512

b) 1/2 ,1/4 ,1/8
a = ½
b = ¼/½ = ½
Un = ½ x ½ⁿ-¹ = ½ⁿ
U8 = ½^8 = 1/256

a.) 4 , -8 , 16 , -32

a = 4

[tex]r = \frac{u2}{u1} \\ r = \frac{ - 8}{4} \\ r = - 2[/tex]

[tex]Un = {ar}^{n - 1} \\ Un = 4( { - 2)}^{n - 1} \\ Un = { - 8}^{n - 1} [/tex]

[tex] Un = {ar}^{n - 1} [/tex]

[tex] U8 = {4}{(-2)}^{8-1} [/tex]

[tex] U8 = {4}{(-2)}^{7} [/tex]

[tex] U8 = {4}{(-128)} [/tex]

[tex] U8 = -512 [/tex]