1+4+7+10...(3n+4)(3n+7)的详细解答过程
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/30 19:19:28
![1+4+7+10...(3n+4)(3n+7)的详细解答过程](/uploads/image/z/5062549-13-9.jpg?t=1%2B4%2B7%2B10...%EF%BC%883n%2B4%EF%BC%89%EF%BC%883n%2B7%EF%BC%89%E7%9A%84%E8%AF%A6%E7%BB%86%E8%A7%A3%E7%AD%94%E8%BF%87%E7%A8%8B)
1+4+7+10...(3n+4)(3n+7)的详细解答过程
1+4+7+10...(3n+4)(3n+7)的详细解答过程
1+4+7+10...(3n+4)(3n+7)的详细解答过程
(1+3n+7)(3n+7-1)/3/2
=(3n+8)(n+2)/2
有(3n+7-1)÷3+1=n+3个
所以原式=(1+3n+7)(n+3)/2
=(2n+4)(n+3)