先化简再求值:-(2x-3y*3y*3y) (2x-2y*2y)-1

3（x-2y）+2（3x+y）=9x-4y（3x²y-2xy²）-（xy²-2x²y)=xy（3x-2y）-xy(y-2x)=xy(5x-3y)=22

xy^3÷(-xy)+(x+2y)(x-2y)=-y^2+x^2-4y^2=x^2-5y^2=2-5=-3再问：不好意思啊！题目......再答：题目怎么了，不影响结果啊。平方还是正的

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

[1/x-y)-1/(x+y)）÷2y/(x平方+2xy+y平方)=(x+y-x+y)/(x-y)(x+y)÷2y/(x+y)²=(x+y)/(x-y)x=根号3+2,y=根号3=(√3+2

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/

(-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+y）2-（x+y）（x+3y）-4y2]÷2y，=[x2+2xy+y2-x2-3xy-xy-3y2-4y2]÷2y=（-2xy-6y2）÷2y=-x-3y，当x=-2，y＝12时，原式=-（-

X-(Y-2X+(3X-2(2X+Y)+5Y))=X-(Y-2X+(3X-4X-2Y+5Y))=X-(Y-2X+(-X+3Y))=X-(Y+3Y-2X-X)=X-4Y+3X=4X-4Y当X-Y=2X-

5x-{2y-3x+[5x-2(y-2x)+3y]}=5x-[2y-3x+(5x-2y+4x+3y)]=5x-[2y-3x+(9x+y)]=5x-(2y-3x+9x+y)=5x-(3y+6x)=5x-

[（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

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

（2x-3y）^2-（x-2y）（x-5y）-（2x+y）（2x-y）=4x^2+9y^2-12xy-(x^2-2yx-5yx+10y^2)-(4x^2-y^2)=4x^2+9y^2-12xy-x^2