简单英文数学问题(geometric sequence)find the sum to infinity of a geometric sequence whose sum to three terms is 3968 with a second term of 640please process,thanks

来源:学生作业帮助网 编辑:作业帮 时间:2024/07/29 21:22:57
简单英文数学问题(geometric sequence)find the sum to infinity of a geometric sequence whose sum to three terms is 3968 with a second term of 640please process,thanks
xQJ@~آ%i"85AmoU[TKA܊n>MgҼ3H^fΌA4gGc:d $6SBķ +#@ɢeo1r S P1&0X T,br+F#9'YF:c [X]_ :yڋ53 u6kmzZ^w:Yt4fWuQ"yKĜfA`kdV"8>xZ ŭz7lm 옾/

简单英文数学问题(geometric sequence)find the sum to infinity of a geometric sequence whose sum to three terms is 3968 with a second term of 640please process,thanks
简单英文数学问题(geometric sequence)
find the sum to infinity of a geometric sequence whose sum to three terms is 3968 with a second term of 640
please process,thanks

简单英文数学问题(geometric sequence)find the sum to infinity of a geometric sequence whose sum to three terms is 3968 with a second term of 640please process,thanks
geometric sequence是等比数列呀
那么设公比是q
就有 640/q+640+640q=3968
所以640q^2-3328q+640=0
q=1/5 or q=5
q=5数列极限是正无穷 和当然也是正无穷吧
q=1/5 那么首项是3200 所以和极限就是3200/(1-q)=4000