Jumlah deret geometri tak hingga 5+√5+1+¹/5√5 adalah? A.5√5 B.1/5√5 C.5+1/5√5 D.5/4(5+√5) E.½(5+√5)

Kelas 9 Matematika
Bab Barisan dan Deret Bilangan

r = U2/U1
r = (√5)/5

S~ = a/(1 - r)
S~ = 5/(5/5 - 1/5 . √5)
S~ = 5/(1/5 . (5 - √5))
S~ = 25/(5 - √5) . (5 + √5)/(5 + √5)
S~ = (25 (5 + √5))/(5² - √5²)
S~ = (25 (5 + √5))/(25 - 5)
S~ = (25/20) (5 + √5)
S~ = (5/4) (5 + √5)

✩✩ D ✩✩

DereT GeoMetRi taK HinggA

5 + √5 + 1 + 1/5 √5
a = 5
r = U2/U1 = U3/U2 = 1/√5

S~ = a/(1 - r)
S~ = 5/(1 - 1/√5)
S~ = 5/((√5 - 1)/√5)
S~ = 5√5 / (√5 - 1)
S~ = 5√5 (√5 + 1) / (5 - 1)
S~ = 1/4 (25 + 5√5)