(a-1)+(a²-2)+...+(a∧n-n) (2-3×5∧-1)+(4-3×5∧-2)+(a-1)+(a²-2)+...+(a∧n-n) (2-3×5∧-1)+(4-3×5∧-2)+...+(2n-3×5∧-n) 两题都是求和,麻烦写下具体过程,谢谢!
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/18 02:44:33
![(a-1)+(a²-2)+...+(a∧n-n) (2-3×5∧-1)+(4-3×5∧-2)+(a-1)+(a²-2)+...+(a∧n-n) (2-3×5∧-1)+(4-3×5∧-2)+...+(2n-3×5∧-n) 两题都是求和,麻烦写下具体过程,谢谢!](/uploads/image/z/1983003-51-3.jpg?t=%EF%BC%88a-1%EF%BC%89%2B%EF%BC%88a%26%23178%3B-2%EF%BC%89%2B...%2B%EF%BC%88a%E2%88%A7n-n%EF%BC%89+%EF%BC%882-3%C3%975%E2%88%A7-1%EF%BC%89%2B%EF%BC%884-3%C3%975%E2%88%A7-2%EF%BC%89%2B%EF%BC%88a-1%EF%BC%89%2B%EF%BC%88a%26%23178%3B-2%EF%BC%89%2B...%2B%EF%BC%88a%E2%88%A7n-n%EF%BC%89++%EF%BC%882-3%C3%975%E2%88%A7-1%EF%BC%89%2B%EF%BC%884-3%C3%975%E2%88%A7-2%EF%BC%89%2B...%2B%EF%BC%882n-3%C3%975%E2%88%A7-n%EF%BC%89++%E4%B8%A4%E9%A2%98%E9%83%BD%E6%98%AF%E6%B1%82%E5%92%8C%2C%E9%BA%BB%E7%83%A6%E5%86%99%E4%B8%8B%E5%85%B7%E4%BD%93%E8%BF%87%E7%A8%8B%2C%E8%B0%A2%E8%B0%A2%21)
(a-1)+(a²-2)+...+(a∧n-n) (2-3×5∧-1)+(4-3×5∧-2)+(a-1)+(a²-2)+...+(a∧n-n) (2-3×5∧-1)+(4-3×5∧-2)+...+(2n-3×5∧-n) 两题都是求和,麻烦写下具体过程,谢谢!
(a-1)+(a²-2)+...+(a∧n-n) (2-3×5∧-1)+(4-3×5∧-2)+
(a-1)+(a²-2)+...+(a∧n-n)
(2-3×5∧-1)+(4-3×5∧-2)+...+(2n-3×5∧-n)
两题都是求和,麻烦写下具体过程,谢谢!
(a-1)+(a²-2)+...+(a∧n-n) (2-3×5∧-1)+(4-3×5∧-2)+(a-1)+(a²-2)+...+(a∧n-n) (2-3×5∧-1)+(4-3×5∧-2)+...+(2n-3×5∧-n) 两题都是求和,麻烦写下具体过程,谢谢!
第二题:(a+a^2+a^3+.a^n)----(1+2+3+.n)=a(1-a^n)/(1-a)-n(n-1)/2=自己合并一下就可以了
第三题:去括号得(2+4+6+.2n)-3*[5^(-1)+5^(-2)+.5^(-n)]=2*(1+2+3+...n)-3*[5^(-1)+5^(-2)+.5^(-n)]=n(n-1)-3/5[1-{5^(-1)^}^n]^4/5=n(n-1)-12/25*[1-{5^(-1)^}^n]=自己合并一下得
括号打开,奇次项求和,偶此项求和,用的是等差和等比的公式。