作业帮2x-x*2分之2y-xy 其中x=-1 y=2
来源：学生作业帮助网 编辑：作业帮 时间：2024/05/18 00:46:30
x(x+y)(x-y)-x(x+y)^2=x(x+y)(x-y-x-y)=-2xy(x+y)=-2x(1/2)x1=-1
原式=x²-2xy+y²-4x²+y²-4x²-2xy=-7x²-4xy+2y²=-7+1+1/8=-47/8a=1,b=-2原式
(x分之x的平方-y的平方)乘以(x的平方-2xy+y的平方分之2x)其中x=2y=1=(x^2-y^2)/x*2x/(x-y)^2=(x+y)(x-y)/x*2x/(x-y)^2=2(x+y)/(x
(xy-x²)÷(x²-2xy+y²)/(x-y)×(x-y)/x²=-x(x-y)÷(x-y)²/x²=-x(x-y)×x²/(
原式=x²y²-4+x²y²+4xy+4=2x²y²+4xy=2*36*4/9+4*6*(-2/3)=16
(x+y)(x-y)-(x的2次方-3xy)=x²-y²-x²+3xy=3xy-y²=3x2x(-1/2)-(-1/2)²=-3-1/4=-3.25
(3x+2y)(4x-5y)-11(x+y)(x-y)+5xy=12x²-7xy-10y²-11x²＋11y²＋5xy=x²-2xy＋y²=
(xy-x²)÷(x²-2xy+y²)/(x-y)×(x-y)/x²=-x(x-y)÷(x-y)²/x²=-x(x-y)×x²/(
（x+2y-3xy)-(-2x-y+xy)=x+2y-3xy+2x+y-xy=(1+2)x+(2+1)y-(3+1)xy=3x+3y-4xy=3(x+y)-4xy=3*1/2-4*(-1/2)=3/2
原式=3x²y-(2xy-2xy+3x²y+xy)=3x²y-(3x²y+xy)=3x²y-3x²y-xy=-xy=-3×(-1/3)=1
原式=(3y-xy)/(x^2-3x)=y(3-x)/x(x-3)=-y/x把x=根号2,y=-2代入原式=-(-2)/√2=√2
[4(xy-1)^2-(xy+2)(2-xy)]除以4分之1xy=[4x^2乘以y^2-8xy+4-(4-x^2y^2)]除以4分之1xy=(4x^2乘以y^2-8xy+4-4+x^2y^2)除以4分
原式=(3y-xy)/(x^2-3x)=y(3-x)/x(x-3)=-y/x=-2/-1=2
2分之1x的平方y-3分之1xy-0.5x的平方y+0.5xy=6分之1xy=6分之1*3*(-2)=-1
解2xy²-[3xy²-2(x²y-1/2xy²)]-2x²y=2xy²-(3xy²-2x²y+xy²)-2x
原式为：x²-3xy／x²-6xy+9y²=x(x－3y)／(x－3y)²=x／x－3y再将x=-1y=3分之2代入,有原式=x／x－3y=﹣1／（﹣1）－3×
[(xy-2)(-xy-2)-4(xy-1)^2]除以(-xy)=[-x²y²+4-4(x²y²-2xy+1)]÷(-xy)=(-x²y²+
原式=(x-y)/x÷[x²-(2xy-y²)]/x=(x-y)/x÷(x²-2xy+y²)/x=(x-y)/x×x/(x-y)²=1/(x-y)=1