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MODUL MTEMATIKA KELAS XII

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1a. Tentukan rumus jumlah n suku pertama dari deret aritmetika 10 + 18 +<br />

26 + . .<br />

S<br />

S<br />

S<br />

S<br />

S<br />

n<br />

n<br />

n<br />

n<br />

n<br />

a = 10<br />

b = 8<br />

1<br />

n2<br />

a ( n 1)<br />

b<br />

2<br />

1<br />

. n2.10<br />

( n 1).8<br />

2<br />

1<br />

. n20<br />

8n<br />

8<br />

2<br />

1<br />

. n12<br />

8n<br />

2<br />

2<br />

6n<br />

4n<br />

<br />

b. Tentukan jumlah 10 suku pertama dari deret aritmetika 10 + 18 + 26 +<br />

. . . .<br />

S<br />

S<br />

S<br />

S<br />

S<br />

10<br />

10<br />

10<br />

10<br />

10<br />

1<br />

n2<br />

a ( n 1)<br />

b<br />

2<br />

1<br />

.102.10<br />

(10 1).8<br />

2<br />

5 20 72<br />

<br />

5.92<br />

460<br />

<br />

<br />

2. Jumlah n buah suku pertama deret aritmetika dinyatakan oleh Sn =<br />

n<br />

(5n 19)<br />

2<br />

Jawab:<br />

Sn =<br />

S1 =<br />

n<br />

(5n 19)<br />

2<br />

. Tentukan Suku pertama dari deret tersebut?<br />

1<br />

(5.119)<br />

2<br />

Sn =<br />

n<br />

(5n 19)<br />

2<br />

1<br />

S2 = (5.2 19)<br />

2<br />

1<br />

1<br />

S1 = (5 19)<br />

S2 = (10 19)<br />

2<br />

2<br />

S1 = 1 .( 14)<br />

2<br />

S2 = 1<br />

.( 9<br />

2<br />

)<br />

Modul Matematika SMK Kelas <strong>XII</strong> Semester I<br />

3

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