Question

Dari deret geometri diketahui U4:U6 = P dan U2.U8 = 1/P maka tentukan U1

Answer 1

U4 : U6 = P
a . r^4-1 : a . r^6-1 = p
a . r^3 : a . r^5 = p
1 / r^2 = p
1 = p . r^2
1/p = r^2

U2 . U8 = 1/p
a . r^2-1 . a . r^8-1 = r^2
a^2 . r^8 = r^2
a^2 = r^2 / r^8
a^2 = 1 / r^6
a = 1 / r^3