Jawapan

  • kin9
  • Tangan Bantuan
2016-02-12T11:44:48+08:00
R = -10/5   a = 5

Sn = a(1-r∧n)÷(1-r)

215 = 5[1-(-2∧n)] ÷ (1-(-2)

215 = 5[1+2∧n]÷3

645 = 5[1+2^n]

129 = [1+2^n]

128 = 2^n

2^7 = 2^n

n = 7





ahh careless nya silap sikit je , btw thank you so muchh