(1)
×(?4)2?0.25×(?5)÷(?5 8
)31 2
=
×16-0.25×5×85 8
=10-10
=0;
(2)(4ay2-3a)+(2+4a-ay2)-(2ay2+a)
=4ay2-3a+2+4a-ay2-2ay2-a
=ay2+2;
(3)
x?(2x?1 2
y2)?(2 3
x?3 2
y2)1 3
=
x-2x+1 2
y2-2 3
x+3 2
y2=-3x+y2,1 3
把x=?
,y=?1 4
代入,-3x+y2=0.75+0.25=1.1 2