当y-x=3时,求代数式1/3×(x-y)³+2(x-y)²-2x+2y-6的值

当y-x=3时,求代数式1/3×(x-y)³+2(x-y)²-2x+2y-6的值
当y-x=3时,求代数式1/3×(x-y)³+2(x-y)²-2x+2y-6的值

当y-x=3时,求代数式1/3×(x-y)³+2(x-y)²-2x+2y-6的值
y-x=3
所以
1/3×(x-y)³+2(x-y)²-2x+2y-6
=1/3×(x-y)³+2(x-y)²-2(x-y)-6
=-1/3×3³+2×3²-2×(-3)-6
=-9+18+6-6
=9

y-x=3
则：x-y=-3
1/3×(x-y)³+2(x-y)²-2x+2y-6
=1/3×(x-y)³+2(x-y)²-2(x-y)-6
=1/3×(-3)³+2×(-3)²-2×(-3)-6
=-9+18+6-6
=9

X-Y=-3，1/3×(x-y)³+2(x-y)²+2y-2x-6=9

1/3×(x-y)³+2(x-y)²-2x+2y-6
=-1/3×(y-x)³+2(y-x)²+2(y-x)-6
=-1/3×3³+2×3²+2×3-6
=9

原式=1/3×(x-y)³+2(x-y)²-2x+2y-6=1/3×(x-y)³+2(x-y)²-（x-y）-6
y-x=3 则x-y=-3 带入原式 得1/3*(-3)3+2(-3)2-2(-3)-6=9 明白