Jawab:
Penjelasan dengan langkah-langkah:
saya jawab yang dilingkarin
1. a. 2+7+17
dit: jumlah deret 10 suku pertama
jawab= rumusnya = sn= a × (r^n-1)/r-1
s10= 2 × (2^9)
=2 × 512 = 1024
c. 10+8+6+4....
dit: jumlah suku ke 10
jawab: rumusnya = sn= n/2 × (2a + (n-1) × b)
s10= 10/2 × (2×10 + 9×-2)
=5 × 2 = 10
2. b. Sn= n² + 4
dit: jumlah suku ke 6
rumusnya s6= 6² +4
=36+4= 40
c. sn = 2^n +1
rumusnya s6= 2^7= 128
4. 12......249
249= 12 + (n-1) 3
237/3=n-1
80=n
s80= 80/2 (12 + 249)
40 × 251 = 10040
b. 102........498
498= 102 + (n-1) 6
396/6= n-1
67=n
s67= 67/2 (102 +498)
67×600/2= 67×300= 20100
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Jawab:
Penjelasan dengan langkah-langkah:
saya jawab yang dilingkarin
1. a. 2+7+17
dit: jumlah deret 10 suku pertama
jawab= rumusnya = sn= a × (r^n-1)/r-1
s10= 2 × (2^9)
=2 × 512 = 1024
c. 10+8+6+4....
dit: jumlah suku ke 10
jawab: rumusnya = sn= n/2 × (2a + (n-1) × b)
s10= 10/2 × (2×10 + 9×-2)
=5 × 2 = 10
2. b. Sn= n² + 4
dit: jumlah suku ke 6
rumusnya s6= 6² +4
=36+4= 40
c. sn = 2^n +1
rumusnya s6= 2^7= 128
4. 12......249
249= 12 + (n-1) 3
237/3=n-1
80=n
s80= 80/2 (12 + 249)
40 × 251 = 10040
b. 102........498
498= 102 + (n-1) 6
396/6= n-1
67=n
s67= 67/2 (102 +498)
67×600/2= 67×300= 20100