先化简再求值:[x+y][x-y]-[x-y]²-6x²y÷2y

原式=（x-y）（x+2y）除以（x-y）（x-y）-(1-x方y的四次方)-x方y的四次方=(x+2y)除以（x-y）-1当x=根3+根2,y=根3-根2上式=（3倍根3-根2）除以（2倍根2）-1

打开括号,3(4x^2+y^2+4xy)-2(x^2+4y^2-4xy)-4(x^2-9y^2)=(12-2-4)x^2+(3-8+36)y^2+(12+8)xy=6x^2+31y^2+20xy代入x

【(x+2y)^2-(x+y)(3x-y)-5y^2】/(2x)=(x^2+4xy^2+4y^2-3x^2-2xy+y^2-5y^2)/(2x)=(-2x^2+4xy^2-2xy)/(2x)=-x+2

2（x+y)(x+y)-(x-y)²+（x-y)²=2(x+y)²-[(x-y)²-(x-y)²]=2(x²+2xy+y²)-0=

原式=(3x²-2x²-2xy+2xy-y²)÷(x+y)=(x²-y²)÷(x+y)=(x+y)(x-y)÷(x+y)=x-y=1/2-1/3=1/

题目和图片对应的?那就先说图片的那个化简原式等于1/(2x)-[(x+y)×(x-y)+(x-y)/(2x)]/(x-y)=1/(2x)-[(x+y+1/(2x)]=-x-y根号下x-1-根号下1-x

(-4x^2)/(-2x)+12x^3y^2/(-4x^2y)-24x^4y^3/(-4x^3y^2)=2x-3xy+6xy=2x+3xy=x(2+3y)=(-2)*(2+3/4)=-2*11/4=-

x^2-4x+y^2+2y+5=0.(x-2)^2+(y+1)^2=0x=2y=-1：（2x+y)(2x-y)-(-2x+y)^2,=4x^2-y^2-4x^2-y^2+4xy=4xy=4*2*1=8

(x+y)/[1/(x^2+y^2)]/(x^4-y^4)=(x+y)(x^2+y^2)/[(x^2-y^2)(x^2+y^2)]=(x+y)/(x^2-y^2)=1/(x-y)=1/(8-11)=-

[（x+2y）²-（x+y)(3x-y)-5y²]÷（2x）,=(x²+4xy+4y²-3x²-2xy+y²-5y²)/(2x)=

解(x-y)(x+y)-(x-2y)²+x(3x-5y)-(x-y)(x-2y)=(x²-y²)-(x²-4xy+4y²)+(3x²-5xy

解题思路：结合完全平方公式变形原式再代入数值进行计算解题过程：解：最终答案：

X平方+Y平方-2X+4Y+5=0=>(x-1)^2+(y+2)^2=0=>x=1,y=-2（2x+y）（2x+y)-(2x-y)平方=8xy=-16

答：x-2【x+2y】+3【2y-x】,其中x=-2,y=1=x-2(x+2y)+3(2y-x)=x-2x-4y+6y-3x=(1-2-3)x+(-4+6)y=-4x+2y=-4*(-2)+2*1=8

-6x^2+3xy+6y^2;12;Matlab:>>symsxy>>f=(x+2*y)^2-(2*x+3*y)*(3*x-2*y)-(x-2*y)^2>>simple(f)>>subs(ans,{x

（x-y）（x-2y）-1/2（2x-3y）（x+2y）,其中x=2,y=2/5=x²-3xy+2y²-1/2(2x²+xy-6y²)=x²-3xy+

等等正在打再答：原式=X^2+Y^2-2XY+6X^2+3XY-4XY-2Y^2-6X^2+XY=X^2-Y^2-2XY=½^2-1-2*½=-7/4再问：∧是什么意思？再问：∧是

2xy/(x^2-y^2)-x/(x+y)+y/(y-x)=2xy/(x^2-y^2)-x/(x+y)-y/(x-y)=2xy/[(x-y)(x+y)]-x(x-y)/[(x-y)(x+y)]-y(x

x²+9y²+4x-18y+13=0.（x²+4x）+（9y²-18y）+（4+9）=0（x²+4x+4）+（9y²-18y+9）=0（x+

原式=(x+y)(x-y-x+2y)/y=(x+y)y/y=x+y因为已知代数式无意义,即：0的0次方无意义,所以3x-2y-7=0及2x+3y+4=0,解得：x=1,y=-2代入x+y=-1