先化简再求值(x-y)(x-2y) (x 2y)(x-3y) x=4,y=1.5
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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/
(-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也有平方的原式=(x²-2xy+y²-x²-2xy-y²)/2xy=-4xy/2xy=-2再问:我是怎么写的最后【-4xy】/(2x)可是再后=-2y再答
(x-y)^2+7(x+y)-11(x-y)^2-8(x+y),=-10(x-y)²-(x+y)当x+y=-3,x-y=-1时=-10*(-1)²-(-3)=-10+3=-7
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+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
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
(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