已知实数-9,a1,a2,-1成等差数列,-9,b1,b2,b3,-1,成等比数列,则a2b2-a1b1等于多少,我要...

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已知实数-9,a1,a2,-1成等差数列,-9,b1,b2,b3,-1,成等比数列,则a2b2-a1b1等于多少,我要...
已知实数-9,a1,a2,-1成等差数列,-9,b1,b2,b3,-1,成等比数列,则a2b2-a1b1等于多少,

-1=-9+3d
d=8/3
a1=-9+d=-19/3
a2=-9+2d=-11/3
-1=-9q^4
q=1/√3
b1=-9q=-3√3
b2=-9q^2=-3
b3=-9q^3=-√3
a2b2-a1b1=11-19√3