已知xy^2=-3,求-xy(x^3y^7-3x^2y^5-y)的值第二步=-(xy^2)^4+3(xy^2)^3+(xy^2)

来源：学生作业帮助网 编辑：作业帮 时间：2024/05/17 07:40:41
已知xy^2=-3,求-xy(x^3y^7-3x^2y^5-y)的值第二步=-(xy^2)^4+3(xy^2)^3+(xy^2)

已知xy^2=-3,求-xy(x^3y^7-3x^2y^5-y)的值第二步=-(xy^2)^4+3(xy^2)^3+(xy^2)
已知xy^2=-3,求-xy(x^3y^7-3x^2y^5-y)的值
第二步
=-(xy^2)^4+3(xy^2)^3+(xy^2)

已知xy^2=-3,求-xy(x^3y^7-3x^2y^5-y)的值第二步=-(xy^2)^4+3(xy^2)^3+(xy^2)
楼主算得对,第一个回答在第二步的地方把三次方的系数 3 弄丢掉了,所以正确的还是-165

-xy(x^3y^7-3x^2y^5-y)
=-x^4y^8+3x^3y^6+xy^2
=-(xy^2)^4+(xy^2)^3+(xy^2)
=-(-3)^4+(-3)^3+(-3)
=-81-27-3
=-111

原式=-x^4y^8+3x^3y^6+xy^2
=-(xy^2)^4+3(xy^2)^3+xy^2
当xy^2=-3时，原式=-（-3）^4+3(-3)^3+(-3)
=(-81）+(-81)+(-3)
=(-3)

已知xy^2=-2,求-xy（x^2y^5-xy^3-y)的值. 已知xy^2=-2 求-xy(x^2y^5-xy^3-y) 已知x^2-xy=5,xy-y^2=-3求3(x^2-xy)-xy+y^2 已知x:y=3:2,求(x²+3xy)/(xy+2xy) 已知xy为正整数,3xy=2x+3y+5.求xy=? 已知X+Y=3XY,求2X+2Y-XY除以X+Y+2XY的值,要算理.已知X+Y=3XY,求2X+2Y-XY除以X+Y+2XY的值,要算理. 已知xy/x+y=3,求2x-3xy+2y/-x+3xy-y的值 已知xy/x+y=3,求2x-3xy+2y/-x+3xy-y的值 已知x-y=3xy,求分式3x+2xy-3y/x-2xy-y的值 已知xy/x+y=2,求代数式3x-xy+3y/-x+3xy-y的值 已知xy/x+y=6,求3x-2xy+3y/-x+3xy-y的值. 已知(xy)/(x+y)=6求(3x-2xy+3y)/(-x+3xy-y)的值. 已知X+Y分之XY=2,求-X+3XY-Y分之3X+5XY+3Y 已知y=3xy+x,求代数式2x+3xy-2y/x-2xy-y的值 已知x-y/xy=3,求分式2x+3xy-2y/x-2xy-y的值. 已知3/(x-y)=1/xy 求(-x-2xy+y)/ (2x+3xy-2y) 已知x-y=3xy,求2x+3xy-2y/x-2xy-y 已知x-y=3xy,求2x-3xy-2y/x-2xy-y