已知x>0,求y=2-3x-4 x的值域
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x^2-4x+y^2-10y+29=0(x^2-4x+4)+(y^2-10y+25)=0(x-2)^2+(y-5)^2=0x=2,y=5x^2y^2+2x^3y^2+x^4y^2=x^2y^2(1+2
x^2+y^2+4x-6y+13=(x+2)^2+(y-3)^2=0所以x=-2y=3所以x^y=-8
(2x+y)/(x^2-2xy+y^2)X(x-y)=(2x+y)/(x-y)²*(x-y)=(2x+y)/(x-y)x-3y=0,x=3y(2x+y)/(x-y)=(6y+y)/(3y-y
x^2-4x+y^2-10y+29=(x^2-4x+4)+(y^2-10y+25)=(x-2)^2+(y-5)^2=0所以x=2,y=5因此X^2Y^2+2X^3Y^2+X^4Y^2=4*25+2*8
4x-2y=0→y=2x,把所有的y都用2x替代.结果是-1/7
x^2-4x+29-10y+y^2=(x-2)^2+(y-5)^2=0x=2y=5x^2y^2+2x^3y^2+x^4y^2=4*25+2*8*25+16*25=900
X+Y分之X-Y等于3x=-2yX+Y分之2(x-y)减X+Y分之3X+Y=(-x-3y)/(x+y)=1
2x=2-3yx>0则2x>0所以2-3y>0y
x^2+3xy-4y^2/y^2=0x/y=-4or1x-y/x+y=5/3or0
因为(x-y)/(x+y)=3,则(x+y)/(x-y)=1/3则5(x-y)(x+y)-(x+y)/2(x-y)=5*3-1/(3*2)=15-1/6=89/6
3x^2+xy-2y^2=0推出(3x-2y)(x+y)=0推出x=-y或x=(2/3)y{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)}/x^2-9y^2推出:{
(x+2)^2+|x+y+5|=0,x+2=0,x+y+5=0x=-2,y=-33(x^2)y-2(x^2)y+2xy-(x^2)y+4x^2-xy=4x^2+xy=4*(-2)^2+(-2)*(-3
即(x-2y)²=0x-2y=0所以x=2y所以原式=(2x²+2xy-xy-y²)/(4x²-4xy+y²)=(2x²+xy-y²
x²+4x+y²-2y+5=0x²+4x+4+y²-2y+1=0(x+2)²+(y-1)²=0所以x+2=0y-1=0则x=-2y=1所以x
(x³+y³)+(x²y+xy²)+(x+y)=0(x+y)(x²-xy+y²)+xy(x+y)+(x+y)=0(x+y)(x²-
(x²-4x+4)+(4y²+8y+4)=0(x-2)²+4(y+1)²=0则:x-2=0且y+1=0得:x=2、y=-1x+y=1
2x+y+3=xy,①若x=1,则y不存在,此时5x+4y无最值;②若x≠1,则y=(2x+3)/(x-1),M=5x+4y=5x+(8x+12)/(x-1)=(5x²+3x+12)/(x-
X*2+Y*2=(X+Y)*2__-2XY;因为X+Y=3;XY=2;所以X*2+Y*2=9-4=5.
x+2=0,x+y+5=0x=-2,y=-33x^2y+{-2X^2y-[-2xy+(x^2y-4x^2)]-xy}=3x^2y-2X^2y+2xy-x^2y+4x^2-xy=4x^2+xy=4*4+
原式=x-x+x-x+……-x+(2-1+4-3+5-4+……+2008-2007-2009)y=0+(1×1004-2009)y=-1005y=1005/2