Question

xiao_hcho_96

求解，我算不出來（這是是非題）

Answer 1

綾

公比為-1/2
-1/32 = 16*(-1/2)^9
-1/32為第9項
代等比級數公式得
S9 = 16[1-(-1/2)^9] / [1-(-1/2)]
= [16 - (-1/2^5)] / (3/2)
= (32 + 1/16)/3
= 513/48