求证s4,s8-s4,s12-s8

S4S8-S4S12-S8S16-S12成等差数列的原因S4S8-S4S12-S8S16-S12成等差数列的原因S4S8-S4S12-S8S16-S12成等差数列的原因把S全部用An表示的式子写出来再

等差数列中,S8-S4=12,求S12=?等差数列中,S8-S4=12,求S12=?等差数列中,S8-S4=12,求S12=?S8-S4=a5+a6+a7+a8=(a5+a8)+(a6+a7)=2(a

等差数列中,S4=S8,则S12=_____.等差数列中,S4=S8,则S12=_____.等差数列中,S4=S8,则S12=_____.Sn=n[a1+(n-1)/2d]S4=S84(a1+3/2d

等差数列An,前N项和为Sn,求证S4,S8-S4,S12-S8成等差数列若等差改成等比,是否仍有此性质?等差数列An,前N项和为Sn,求证S4,S8-S4,S12-S8成等差数列若等差改成等比,是否

设等比数列｛an｝的前n项和为Sn,若S8/S4=3,则S12/S8=?设等比数列｛an｝的前n项和为Sn,若S8/S4=3,则S12/S8=?设等比数列｛an｝的前n项和为Sn,若S8/S4=3,则

已知等差数列an的前n项和为Sn,S4/S8=1/2,那么S8/S12=?已知等差数列an的前n项和为Sn,S4/S8=1/2,那么S8/S12=?已知等差数列an的前n项和为Sn,S4/S8=1/2

设等比数列{an}前n项和为Sn,若S8:S4=2:3,则S12:S4=?9设等比数列{an}前n项和为Sn,若S8:S4=2:3,则S12:S4=?9设等比数列{an}前n项和为Sn,若S8:S4=

数列推导设等差数列An的前n项和为Sn,则S4,S8-S4,S12-S8,S16-S12成等差数列,设等差数列An的前n项和为Sn,则S4,S8-S4,S12-S8,S16-S12成等差数列,类比以上

在等差数列{an}中,S4=6,S8=10,则S12=在等差数列{an}中,S4=6,S8=10,则S12=在等差数列{an}中,S4=6,S8=10,则S12=因为是等差数列所以S4,S8-S4,S

sn为等差数列an的前n项和,S8-S4=12,则S12sn为等差数列an的前n项和,S8-S4=12,则S12sn为等差数列an的前n项和,S8-S4=12,则S12s8-s4=a5++a6+a7+

等差数列{an}中,S4=32,S8=56,则S12=?等差数列{an}中,S4=32,S8=56,则S12=?等差数列{an}中,S4=32,S8=56,则S12=?S8-S4=a5+a6+a7+a

等差数列{an},s4=7,s12=90,则s8等于?等差数列{an},s4=7,s12=90,则s8等于?等差数列{an},s4=7,s12=90,则s8等于?等差数列中,S4,S8-S4,S12-

在等差数列｛an｝中,已知S4=4,S8=16,则S12在等差数列｛an｝中,已知S4=4,S8=16,则S12在等差数列｛an｝中,已知S4=4,S8=16,则S12解an是等差数列∴s4,s8-s

等比数列｛an｝前n项和为Sn,S4=2,S8=6,求S12.等比数列｛an｝前n项和为Sn,S4=2,S8=6,求S12.等比数列｛an｝前n项和为Sn,S4=2,S8=6,求S12.因为等比数列｛

等比数列an前n项和Sn若S4=1S12=7则S8等比数列an前n项和Sn若S4=1S12=7则S8等比数列an前n项和Sn若S4=1S12=7则S8s4,s8-s4,s12-s8也成等比数列(s8-

等比数列an中,S4=1,S12=73,则S8=等比数列an中,S4=1,S12=73,则S8=等比数列an中,S4=1,S12=73,则S8=注意一个事实就行了(a12+a11+a10+a9)=(a

等比数列an中,S4=1,S12=73,则S8=等比数列an中,S4=1,S12=73,则S8=等比数列an中,S4=1,S12=73,则S8=因为有:(a12+a11+a10+a9)=(a8+a7+

等比数列{an}中,s4=1,s8=4,则s12=多少?急用!等比数列{an}中,s4=1,s8=4,则s12=多少?急用!等比数列{an}中,s4=1,s8=4,则s12=多少?急用!sn=a1(1

在等比数列｛an｝中,已知S4=1,S8=17则S12=?在等比数列｛an｝中,已知S4=1,S8=17则S12=?在等比数列｛an｝中,已知S4=1,S8=17则S12=?等于33s4=a1+a2+

等比数列中{an}草药S4=2S8=8求S12等比数列中{an}草药S4=2S8=8求S12等比数列中{an}草药S4=2S8=8求S12s4,s8-s4,s12-s8也成等比数列,s12-s8=6*