Question

Ada yang bisa jawab? kalo nisa kasih caranya yaa:)

Answer 1

1. a =9
b = 2
Un = 47
a + (n-1) b = 47
9 + (n-1) 2 = 47
9 + 2n - 2 = 47
2n + 7 = 47
2n = 40
n = 20
Sn = n/2(2a + (n-1)b)
     = n/2 (a + Un)
     =  20/2 (9 + 47)
     = 10 (56)
   = 560
2. a = 5
b = 6
Un = 89
a + (n - 1) 6 = 89
5 + 6n - 6 = 89
6n - 1 = 89
6n = 90
n = 15
Sn = n/2 (a + Un)
   = 15/2 (5 + 89)
   = 15/2 (94)
   = 15 (47)
= 705
3. a = 16
b = -3
Un = -35
a + (n-1) b = -35
16 - 3n + 3 = -35
19 - 3n = -35
54 = 3n
n = 18
Sn = 18/2 (16 - 35)
     = 9 (-19) = -171
4. a = 15
b = 5
Un = 105
a + (n-1)b = 105
15 + 5n - 5 = 105
5n + 10 = 105
5n = 95
n = 19
Sn = 19/2 (15 + 105)
   = 19/2 (120) = 19 (60) = 1.140
5. bil pertama antara 20 - 200 yg habis dibagi 6 = 24
bil terakhir = 198
a = 24
b = 6
Un = 198
a + (n - 1) b = 198
24 + 6n - 6 = 198
18 + 6n = 198
6n = 180
n = 30
Sn = 30/2 ( 24 + 198)
   = 15 ( 222) = 3.330