" Life is not a problem to be solved but a reality to be experienced! "
© Copyright 2013 - 2024 KUDO.TIPS - All rights reserved.
Verified answer
MAPEL = MATEMATIKAKELAS = 9
BAB = BARISAN & DERET
diketahui :
U2 = 19
U5 = 31
ditanya : U50 dan S30 ??
---------- Barisan Aritmatika ---------
U2 = 19
➡ a + b = 19......... ( 1 )
U5 = 31
➡ a + 4b = 31........( 2 )
eliminasi nilai a pada pers. ( 1 ) dan ( 2 )
a + 4b = 31
a + b = 19
_________-
3b = 12
b = 12/3
b = 4
subtitusi nilai b = 4 pada pers. ( 1 )
a + b = 19
a + 4 = 19
a = 19 - 4
a = 15
U50 = a + ( n - 1 )b
U50 = 15 + ( 50 - 1 )( 4 )
U50 = 15 + 196
U50 = 211
S30 = n/2[ 2a + ( n - 1 )b ]
S30 = 30/2[ 2(15) + ( 30 - 1 )(4) ]
S30 = 15[ 30 + 116 ]
S30 = 15[ 146 ]
S30 = 2190
jadi,
suku ke-50 = 211 dan,
jumlah 30 suku pertama = 2190
semoga membantu