当x=-2,y=2/3求3y^4-4x^2y-4y^4+2x^2y-x^2y的值

当x=-2,y=2/3求3y^4-4x^2y-4y^4+2x^2y-x^2y的值
当x=-2,y=2/3求3y^4-4x^2y-4y^4+2x^2y-x^2y的值

当x=-2,y=2/3求3y^4-4x^2y-4y^4+2x^2y-x^2y的值
先化简：3y^4-4x^2y-4y^4+2x^2y-x^2y＝=-y^4-3x^2y
再将x=-2,y=2/3代入,得－(2/3)^4－3*(-2)^2*(2/3)=-8又16/81

3y^4-4x^2y-4y^4+2x^2y-x^2y=-y^4-3x^2y=-（2/3)^4-3*(-2)^(4/3)=-16/81-6* 2^(1/3)