-4/9,10/9,4/3,7/9,1/9 A.7/3 B 10/9 C -5/18 D -2 -4/9,10/9,4/3,7/9,1/9 A.7/3 B 10/9 C -5/18 D -2

-4/9,10/9,4/3,7/9,1/9 A.7/3 B 10/9 C -5/18 D -2 -4/9,10/9,4/3,7/9,1/9 A.7/3 B 10/9 C -5/18 D -2

選C
設a1=-4/9
a2=10/9
.
a4=(a2-a1)/2
a5=(a3-a2)/2
a6=(a4-a3)/2=(7/9-4/3)/2=-5/18