以知数列{An}是等差数列,{Sn}是其前n项的和,求证:S6,S12-S6,S18-S12 成等差数列.设K∈N* Sk,S2k-Sk,S3k-S2k 成等差数列吗.A= S6=6*(a1+a6)/2=3(a1+a6) B= S12-S6=6*(a1+a12)/2-6*(a1+a6)/2=3(a12-a6) C= S18-S12=6*(a1+a18)/2-6*(a
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/25 16:54:11
![以知数列{An}是等差数列,{Sn}是其前n项的和,求证:S6,S12-S6,S18-S12 成等差数列.设K∈N* Sk,S2k-Sk,S3k-S2k 成等差数列吗.A= S6=6*(a1+a6)/2=3(a1+a6) B= S12-S6=6*(a1+a12)/2-6*(a1+a6)/2=3(a12-a6) C= S18-S12=6*(a1+a18)/2-6*(a](/uploads/image/z/8845543-55-3.jpg?t=%E4%BB%A5%E7%9F%A5%E6%95%B0%E5%88%97%7BAn%7D%E6%98%AF%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%2C%7BSn%7D%E6%98%AF%E5%85%B6%E5%89%8Dn%E9%A1%B9%E7%9A%84%E5%92%8C%2C%E6%B1%82%E8%AF%81%EF%BC%9AS6%2CS12-S6%2CS18-S12+%E6%88%90%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97.%E8%AE%BEK%E2%88%88N%2A+Sk%2CS2k-Sk%2CS3k-S2k+%E6%88%90%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%E5%90%97.A%3D+S6%3D6%2A%28a1%2Ba6%29%2F2%3D3%28a1%2Ba6%29+B%3D+S12-S6%3D6%2A%28a1%2Ba12%29%2F2-6%2A%28a1%2Ba6%29%2F2%3D3%EF%BC%88a12-a6%EF%BC%89+C%3D+S18-S12%3D6%2A%28a1%2Ba18%29%2F2-6%2A%28a)
以知数列{An}是等差数列,{Sn}是其前n项的和,求证:S6,S12-S6,S18-S12 成等差数列.设K∈N* Sk,S2k-Sk,S3k-S2k 成等差数列吗.A= S6=6*(a1+a6)/2=3(a1+a6) B= S12-S6=6*(a1+a12)/2-6*(a1+a6)/2=3(a12-a6) C= S18-S12=6*(a1+a18)/2-6*(a
以知数列{An}是等差数列,{Sn}是其前n项的和,求证:S6,S12-S6,S18-S12 成等差数列.
设K∈N* Sk,S2k-Sk,S3k-S2k 成等差数列吗.
A= S6=6*(a1+a6)/2=3(a1+a6)
B= S12-S6=6*(a1+a12)/2-6*(a1+a6)/2=3(a12-a6)
C= S18-S12=6*(a1+a18)/2-6*(a1+a12)/2=3(a18-a12)
满足 2B=A+C
但是B= S12-S6=6*(a1+a12)/2-6*(a1+a6)/2=3(a12-a6)中为什么是6*(a1+a12),和C= S18-S12=6*(a1+a18)/2-6*(a1+a12)/2=3(a18-a12)中为什么是6*(a1+a18)
以知数列{An}是等差数列,{Sn}是其前n项的和,求证:S6,S12-S6,S18-S12 成等差数列.设K∈N* Sk,S2k-Sk,S3k-S2k 成等差数列吗.A= S6=6*(a1+a6)/2=3(a1+a6) B= S12-S6=6*(a1+a12)/2-6*(a1+a6)/2=3(a12-a6) C= S18-S12=6*(a1+a18)/2-6*(a
A= S6=6*(a1+a6)/2=3(a1+a6)
B= S12-S6=6*(a1+a12)/2-6*(a1+a6)/2=3(a12-a6)
C= S18-S12=6*(a1+a18)/2-6*(a1+a12)/2=3(a18-a12)
满足 2B=A+C
得证
设K∈N* Sk,S2k-Sk,S3k-S2k也成等差