已知数列-1,a1,a2,-4成等差数列,-1,b1,b2,b3,-16成等差数列,则a2-a1/b2等于多少

已知数列-1,a1,a2,-4成等差数列,-1,b1,b2,b3,-16成等差数列,则a2-a1/b2等于多少
已知数列-1,a1,a2,-4成等差数列,-1,b1,b2,b3,-16成等差数列,则a2-a1/b2等于多少

已知数列-1,a1,a2,-4成等差数列,-1,b1,b2,b3,-16成等差数列,则a2-a1/b2等于多少
-1+3a=-4,a=-1,a1=-2,a2=-3
-1*q^4=-16,q=+/-2,b2=-4
所以=1/4

a1=-2,a2=-3
b1=-9/4
b2=-7/2
b3=-19/4
所以是2/7

a1=-2，a2=-3
b1=-4，b2=-8，b3=-12
带入式中 -3-（-2）/（-8）=-2.75