5+13+21+….+181=…
Jawaban Terkonfirmasi
Materi : deret aritmatika
a = 5
b = 8
Un = 181
Sn…..?
jawab :
181 = a + bn – b
181 = 5 + 8n – 8
181 = -3 + 8n
184 = 8n
23 = n
Sn = n/2 (a + Un)
S23 = 23/2 (5 + 181)
S23 = 23/2 (186)
S23 = 23 x 93 = 2.139
maaf kalau salah, semoga membantu