为什么a3*a4=a1*a6=a2*a5

A1+A3+A5+A7=4,求A2+A4+A6 a2*a6=4,求a1*a2*a3*a4*a5*a6*a7 等比数列an中,a1+a2+a3+a4+a5=31,a2+a3+a4+a5+a6=62,则通项公式为? a1=8,a7=5832,a1/a2=a2/a3=a3/a4=a4/a5=a5/a6=a6/a7,求a5的值 已知集合A={a1,a2,a3,a4,a5,a6,a7},A并上B={a1,a2,a3,a4,a5,a6,a7,.,a1 等比数列,a1+a2+a3=6,a2+a3+a4=3,求a3+a4+a5+a6+a7+a8=? 已知一列数a1,a2,a3,a4,a5,a6,a7,且a1=1,a7=729,a1/a2=a2/a3=a3/a4=a4/ 若集合A={a1,a2,a3,a4,a5,a6｝,B={a1^2,a2^2,a3^2,a4^2,a5^2,a6^2},其 已知集合A={a1,a2,a3,a4,a5,a6,a7},A∪B={a1,a2,a3,a4,a5,a6,a7.,a100 设数列ai>0.且a1+a2+a3+a4+a5+a6+a7+a8+a9+a10=30,a1*a2*a3*a4*a5*a6 等比数列中,已知a1+a2+a2+a3=7,a4+a5+a6=56,求公比 公比Q=2 a2+a4+a6+...+a100=100 a1+a3+a5+...+a99=?