解
3(x-1)³y-(1-x)³z
=3(x-1)³y+(x-1)³z
=(x-1)³(3y+z)
=(1/2-1)³(3×1/5+6/5)
=-1/8×(9/5)
=-9/40我算也是-9/40，可是答案是3/40z=-6/5还是z=6/5如果是z=-6/5那么3(x-1)³y-(1-x)³z=3(x-1)³y+(x-1)³z=(x-1)³(3y+z)=(1/2-1)³(3×1/5-6/5)=-1/8×(-3/5)=3/40