LATIHAN SOAL BARIS DAN DERET

SOAL

1. Tentukan suku ke 6,10,dan 20 dari deret berikut 7,12,17,22,27 !
2. Tentukan jumlah deret ke 6,10,20 dari deret berikut 2,4,6,8,10 !
3. Tentukan suku ke 5 dan 10 , jika suku pertama 200 dan bedanya 25 !

JAWAB

1.a

Sn = a + (n-1)b

S6 = 7 + (6-1)5

S6 = 7 + 5.5

S6 = 7 + 25

S6 = 32

1.b

S10 = 7 + (10-1)5

S10 = 7 + 9.5

S10 = 52

1.c

S20 = 7 + (20-1)5

S20 = 7 + 19.5

S10 = 102

2.a

J6 = n/2 ( 2a + (n - 1) b)

J6 = 6/2 ( 2.2 + (6 – 1) 2)

J6 = 3 ( 4 + 5.2 )

J6 = 3 ( 4 + 10 )

J6 = 3. 14

J6 = 42

2.b

J10 = 10/2 (2.2+ (10-1)2)

J10 = 5 (4 + 9. 2)

J10 = 5 (4 + 18)

J10 = 5. 22

J10 = 110

2.c

J20 = 20/2 ( 2.2 + (20-1)2)

J20 = 10 (4+ 19.2)

J20 = 10 (4 + 38)

J20 = 10. 42

J20= 420

Dik :

a= 200

b= 25

3.a

Sn = a + (n-1)b

S5 = 200 + (5-1)25

S5 = 200 + 4. 25

S5 = 200 + 100

S5 = 300

3.b

Sn = a + (n-1)b

S10 = 200 + (10-1)25

S10 = 200 + 9. 25

S10 = 200 + 225

S10 = 425