解答 - 几何数列

要找到系列的通用形式，将第一项：$$a=612$$ 和公比：$$r=0.8529411764705882$$ 插入几何级数的公式：

$$a_1=612$$

$$a_2=a_1·r^{n-1}=612\cdot {0.8529411764705882}^{2-1}=612\cdot {0.8529411764705882}^1=612\cdot 0.8529411764705882=522$$

$$a_3=a_1·r^{n-1}=612\cdot {0.8529411764705882}^{3-1}=612\cdot {0.8529411764705882}^2=612\cdot 0.7275086505190311=445.2352941176471$$

$$a_4=a_1·r^{n-1}=612\cdot {0.8529411764705882}^{4-1}=612\cdot {0.8529411764705882}^3=612\cdot 0.6205220842662323=379.7595155709342$$

$$a_5=a_1·r^{n-1}=612\cdot {0.8529411764705882}^{5-1}=612\cdot {0.8529411764705882}^4=612\cdot 0.5292688365800217=323.91252798697326$$

$$a_6=a_1·r^{n-1}=612\cdot {0.8529411764705882}^{6-1}=612\cdot {0.8529411764705882}^5=612\cdot 0.4514351841417832=276.27833269477134$$

$$a_7=a_1·r^{n-1}=612\cdot {0.8529411764705882}^{7-1}=612\cdot {0.8529411764705882}^6=612\cdot 0.3850476570621092=235.64916612201083$$

$$a_8=a_1·r^{n-1}=612\cdot {0.8529411764705882}^{8-1}=612\cdot {0.8529411764705882}^7=612\cdot 0.328423001611799=200.994876986421$$

$$a_9=a_1·r^{n-1}=612\cdot {0.8529411764705882}^{9-1}=612\cdot {0.8529411764705882}^8=612\cdot 0.2801255013747697=171.43680684135907$$

$$a_{10}=a_1·r^{n-1}=612\cdot {0.8529411764705882}^{10-1}=612\cdot {0.8529411764705882}^9=612\cdot 0.23893057470200946=146.2255117176298$$