a4/a1=q³a5/a2=q³a6/a3=q³所以a4a5a6/a1a2a3=q^9=2同理a7a8a9/a4a5a6=q^9a10a11a12=a7a8a9=q^9所以a7a8a9=2*2=4a10a11a12=4*2=8原式=32
32
