已知-9,a1,a2,a3,-1五个实数成等差数列，-9,b1,b2,b3,-1五个实数成等比数列，则a1-a3b2=　 ( )

题干

已知-9,a1,a2,a3,-1五个实数成等差数列，-9,b1,b2,b3,-1五个实数成等比数列，则

a

1

-

a

3

b

2

=　 ( )

A： $\pm \frac{2}{3}$ 　

B： $- \frac{4}{3}$

C： $\frac{4}{3}$

D： $\frac{2}{3}$

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C

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