✔ 最佳答案
find the sum of the terms of the following geometric series.
1) 8－16 ＋32－64＋.....to
10terms
Sol
A=8－16＋32－64＋128－256＋512－1024＋2048－4096
2A = 16－32＋64－128＋256－512＋1024－2048＋4096－8192
3A =8－8192
3A =－8184
A=－2728
2) －1＋0.6－0.36＋...... to
7terms
Sol
A=－1＋0.6－0.36＋.... to
7terms
－A=1－0.6＋0.36＋.... to 7terms
－A=(－0.6)^0+(－0.6)^1+(－0.6)^2+(－0.6)^3+(－0.6)^4+(－0.6)^5+(－0.6)^6
0.6A = (－0.6)^1+(－0.6)^2+(－0.6)^3+(－0.6)^4+(－0.6)^5+(－0.6)^6+(－0.6)^7
－A－0.6A=(－0.6)^0－(－0.6)^7
－1.6A=1+ 0.0279936
A=－0.642496
find the number of terms and the sum of the terms of the following geometric
series.
3) 2－6 +.....+ 512－2048
Sol
－6改為－8
A=2－8＋32－128＋512－2048
4A = 8－32+128－512＋2048－8192
5A =2－8192
A=－1638
