已知x=3y,试求(x+y)^2+2xy-y^2/x^2+7xy+y^2的值

来源：学生作业帮助网编辑：作业帮时间：2024/05/09 22:58:29

已知x=3y,试求(x+y)^2+2xy-y^2/x^2+7xy+y^2的值
已知x=3y,试求(x+y)^2+2xy-y^2/x^2+7xy+y^2的值

已知x=3y,试求(x+y)^2+2xy-y^2/x^2+7xy+y^2的值
原式=（4y)^2+2*3y*y-y^2/9y^2+7*3y*y+y^2
=16y^2+6y^2-1/9+21y^2+y^2
=44y^2-1/9

直接代入都可以求出来，化简一下就算起来简单点：（x+y-y）(x+y+y)+2xy/(x+y)^2+5xy=x(x+2y)+2xy/(x+y)^2+5xy=x^2+2xy+2xy/(x+y)^2+5xy=x^2+4xy/x^2+y^2+7xy代入x=3y得：9y^2+12y^2/10y^2+21y^2=21y^2/31y^2=21/31

已知x=3y,试求（x-y)^2+2xy-y^2/x^2+7xy+y^2 已知x=3y,试求(x-y)^2+2xy-y^2/x^2+7xy+y^2 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:x/y=-2,求x^2-2xy-3y^2/x^-6xy 已知xy=-2,x-y=3,求（x+y)（x-y)-y^2+（x-y)^2-（6x^2y-2xy^2)÷2y 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 已知y=3xy+x,求代数式2x+3xy-2y/x-2xy-y的值已知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x+y=3xy,求2x+2y-xy/x+y+2xy的值、已知x-y=4xy,求2x+3xy-2y/x-2xy-y的值已知X-XY-2Y=0求2X+3XY-Y/X-2XY+5Y 已知x-y=4xy,求x-2xy-y分之2x+3xy-2y的值!