Sn=7n²-3n tentukan U8
Matematika
Qurrotulparkhy
Pertanyaan
Sn=7n²-3n tentukan U8
1 Jawaban
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1. Jawaban nurrafi77
Sn = 7n² - 3n
S1 = 7(1)² - 3(1)
= 7 - 3
= 4
S2 = 7(2)² - 3(2)
= 28 - 6
= 22
U2 = S2 - S1
= 22 - 4
= 18
S1 = U1 = a = 4
b = U2 - U1
= 18 - 4
= 14
Un = a + (n - 1)b
U8 = 4 + (8 - 1)14
= 102