先化简再求值(x-2y)(x 3y)-(2x-y)(x-4y)
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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
原式=3x3-(x3+6x2-7x)-2x3+6x2+8x,=3x3-x3-6x2+7x-2x3+6x2+8x,=15x,当x=-1时,原式=15x=15×(-1)=-15.
3(x-2y)+2(3x+y)=9x-4y(3x²y-2xy²)-(xy²-2x²y)=xy(3x-2y)-xy(y-2x)=xy(5x-3y)=22
原式=3x3-x3-2x3-6x2+6x2+7x+4x=15x,当x=13时,原式=15×13=-5.
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
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/
原式=-x2+x(4分),当x=-1时,原式=-2.
(-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=-
x²-4y²分之x+2y=[(x-2y)(x+2y)]分之x+2y=x-2y分之1=5-2*3.5=-2
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^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
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
y(x+y)+(x-y)2-x2-2y2=xy+y2+x2-2xy+y2-x2-2y2=-xy=-(-13)×3=1
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
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
原式=2x3+4x-2x2-x-3x2+2x3=4x3-5x2+3x,当x=-2时,原式=-32-20-6=-58.