Question

bantuu...............​

Answer 1

BArisan dan DEret
Aritmatika

Penjelasan dengan langkah-langkah:

U8 = 23
u30 = 89
tentukan  S50

u30 - u8 = 89-23
22b = 66
b = 3

u8 = 23
a + 7b =  23
a+  7(3) = 23
a+  21=  23
a= 2

jumlah 50 suku = S50
Sn =  n/2 { 2a +  (n-1) b}
s50=  50/2 { 2 (2) + 49(3)}
s50 = 25 (4 + 147)
s50 = 3.775

Answer 2

S50 = 3.775

Penjelasan dengan langkah-langkah:

U8 = a + 7b = 23

U30 = a + 29b = 89

Eliminasi a

a + 29b = 89

a + 7b = 23

--------------------

29b - 7b = 89 - 23

22b = 66

b = 66/22

b = 3

Substitusi b

a + 7b = 23

a + 7 × 3 = 23

a + 21 = 23

a = 23 - 21

a = 2

50 suku pertama

Sn = n/2 (2a + (n - 1) b)

S50 = 50/2 (2 × 2 + (50 - 1) 3)

S50 = 25 (4 + 49 × 3)

S50 = 25 (4 + 147)

S50 = 25 × 151

S50 = 3.775