先化简,在求值,x-y分之1 (y分之1-x分之1)
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再问:应该30才对再问:负负得正再答:好吧。。
2分之1x-2(x-3分之1y²)+(3分之1y²-2分之3x)=1/2x-2x+2/3y²+1/3y²-3/2x=-3x+y²=-3x2/3+(-2
y的平方-xy分之(x+y)的平方÷{-(x-y)的平方分之y的平方+xy}=(x+y)²/[y(y-x)]÷[-y(y+x)/(x-y)²]=(x+y)²/[y(x-y
x√(1/x)+√4y-2分之√x+1/y√y³=√x+2√y-√x/2+√y=3√y当x=4,y=1/9时,原式=3√y=1
x(3y+2)-(x+1)(3y+2)=(3y+2)(x-x-1)=-3y-2当x=-83/159,x=-1/3时原式=-3*(-1/3)-2=1-2=-1
原式=x^2+4xy+4y^2-x^2+y^2-5y^2=4xy代x=-2,y=1/2入得原式=-2*4*1/2=-4
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/>原式=[(x²-2xy+y²)/(x²-xy)]÷(x/y-y/x)={(x-y)²/[x(x-y)]}÷[(x²-y²)/(xy)]=
(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)=-
原式=(3y-xy)/(x^2-3x)=y(3-x)/x(x-3)=-y/x=-2/-1=2
(2x+y)(2x-y)(4x平方+y平方)=(4x^2-y^2)(4x^2+y^2)=16x^4-y^4=16*(1/2)^4-(1/3)^4=80/81
(2X+3y)的平方-(2x+y)(2x-y),=4x方+12xy+9y方-(4x方-y方)=4x方+12xy+9y方-4x方+y方=12xy+10y方=12×2分之1×(-2分之1)+10×(-2分
|x+1|+(y+2分之1)的平方=0x+1=0y+2分之1=0x=-1y=-2分之13X-2y-[-4x+(y+3x)]-(2x-3y)=3X-2y-(-4x+y+3x)-2x+3y=3X-2y+4
根号2x乘以根号y分之x乘以(根号x分之y除以根号y分之一)=根号2x^2/y*(根号y/x*根号y)=根号2x^2/y*根号y^2/x=根号2x/y再代入x、y的值就可以了.
2(x+x²y)-3分之2(6x²y+3x)-y=2x+2x²y-4x²y-2x-y=-2x²y-y=-2×1²×3-3=-9
2(3x-y)²-4(3x-y)+5(3x-y)²-6(3x-y)其中x=12分之5y=-4分之1=7(3x-y)²-10(3x-y)=(3x-y)(21x-7y-10)
(x-y分之1+x+y分之1)÷x²-y²分之xy=(x+y+x-y)/(x²-y²)×(x²-y²)/xy=2x/xy=2/y=2/根号2
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
这里^2指2次方1/2为2分之1y(x+y)-(2x+y)(x-y)-x^2=xy+y^2-(2x^2-2xy+xy-y^2)-x^2=xy+y^2-2x^2+xy+y^2-x^2=2y^2+2xy-