tentukan nilai x Dari barisan geometri 3 suku pertama x-2, x+4, 4x+7 kemudian tentukan u5

Kelas 8 Matematika
Bab Barisan dan Deret Bilangan

(U2)² = U1 . U3
(x + 4)² = (x - 2) (4x + 7)
x² + 8x + 16 = 4x² + 7x - 8x - 14
x² - 4x² + 8x + x + 16 + 14 = 0
-3x² + 9x + 30 = 0
x² - 3x - 10 = 0
(x - 5) (x + 2) = 0
x + 2 = 0
x = -2

x - 5 = 0
x = 5

r = U2/U1
r = (x + 4)/(x - 2)
r = (5 + 4)/(5 - 2)
r = 3

r = (-2 + 4)/(-2 - 2)
r = 2/-4
r = -1/2

U5 = U1 . r^4
U5 = 3 . 3^4
U5 = 243

U5 = U1 . r^4
U5 = 2 . (-1/2)^4
U5 = 2 . 1/16
U5 = 1/8