先化简在求值,5xyz-{2x2y-[3xyz-(4xy2-x2y)]}其中x=-2,y=-1,z=3

5xyz-{2x^2y-[3xyz-(4xy^2-x^2y)]}
=5xyz-[2x^2y-3xyz+4xy^2-x^2y]
=5xyz-2x^2y+3xyz-4xy^2+x^2y
=8xyz-x^2y-4xy^2

x=-2,y=-1,z=3时
原式=8*(-2)*(-1)*3-(-2)^2*(-1)-4*(-2)*(-1)^2
=48+4+8
=60

计算到不难,楼主考察我们的是读题能力啊...唉..
原式=5xyz-(4xy-(3xyz-(8xy-2xy)))
=5xyz-(4xy-3xyz+6xy)
=5xyz+3xyz-10xy
=xy(8z-10)
=-2*(-1)*(8*3-10)
=28
或者5xyz-{2x^2y-[3xyz-(4xy^2-x^2y)]}
=5xyz-2x^2y+3xyz-4xy^2+x^2y
=8xyz-x^2y-4xy^2
=xy(8z-x-4y)
=60

5xyz-{2x2y-[3xyz-(4xy2-x2y)]}
=5xyz-{2x2y-[3xyz-4xy2+x2y]}
=5xyz-{2x2y+3xyz+4xy2-x2y}
=8xyz-x2y-4xy2
=xy(8z-x-4y)
其中x=-2,y=-1,z=3
xy=2,8z-x-4y=30
5xyz-{2x2y-[3xyz-(4xy2-x2y)]}
=xy(8z-x-4y)
=2*30=60

5xyz-{2x^2y-[3xyz-(4xy^2-x^2y)]}
=5xyz-2x^2y+3xyz-4xy^2+x^2y
=8xyz-x^2y-4xy^2
=xy(8z-x-4y)
=60

其中x^2 y^2分别表示X和Y的平方

原式=5xyz-(4xy-(3xyz-(8xy-2xy)))
=5xyz-(4xy-3xyz+6xy)
=5xyz+