如果X-2Y=0,XY=2,求X的平方 4Y平方
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答:x+y=-3,xy=-2x³y²+x²y³=(x+y)(xy)²=(-3)*(-2)²=-3*4=-12再问:确定么急的、再答:没有错误
x-xy=8(1)xy-y=-9(2)则有(1)-(2):X-XY-XY+Y=X+Y-2XY=8-(-9)=17
(x^2+xy+2y^2)/(x^2-xy+y^2)=[(x/y)²+(x/y)+2]/[(x/y)²-(x/y)+1]分子分母同时除以y²=(4/9+2/3+2)/(4
3x*+xy-2y*=0(3x-2y)(x+y)=0那么x=2y/3或x=-yy/x=3/2或x/y=-1(x/y)-(y/x)-(x*+y*)/(xy)=(x/y)-(y/x)-(x/y+y/x)=
x^2+xy+y=14y^2+xy+x=28两式相加x^2+y^2+2xy+x+y=42(x+y)^2+(x+y)-42=0(x+y-6)(x+y+7)=0x+y=6或x+y=-7
即x=y=1xy=1对不对?如果对的话x^2+2y^2-2xy-2y+1=0化简为你做的很对.就是这样解的,没有其他更好的方法了.这里用到的是数学里的
y-x-2xy=0y-x=2xyx-y=-2xy(3x+xy-3y)/(y-xy-x)=[3(x-y)+xy]/[(y-x)-xy]=(-6xy+xy)/(2xy-xy)=-5xy/xy=-5
x=-2y(2xy+y^2)/(x^2-xy)=(-4y^2+y^2)/(4y^2+2y^2)=-3y^2/(6y^2)=-1/2再问:我算出来也是-1/2,可答案说是-15/28
因为x+2y=0,所以x=-2y原式=(x^2+2xy)/(xy+y^2)=(4y^2-4Y^2)/(-3y^2+y^2)=0/(-2y^2)又因为xy不等于零,所以x、y君不等于零,所以-2y^2亦
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:{
如果有理数xy满足丨x-1丨+(xy-2)²=0求x和y的值丨x-1丨+(xy-2)²=0丨x-1丨=0x=1(xy-2)²=0xy=2y=2
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
x+2y=0,xy不等于0∴x=-2yx²+2xy/xy+y²=(4y²-4y²)/(-2y²+y²)=0
y-x-2xy=0所以x-y=-2xyy-x=2xy所以原式=[3(x-y)+xy]\[(y-x)-xy]=[3×(-2xy)+xy]\(2xy-xy)=-5xy\xy=-5
xy/(x+y)=2,1/x+1/y=2(3x-5xy+3y)/(-x+3xy-y)=(3/y+3/x-5)/(-1/y-1/x+3)=(6-5)/(-2+3)=1题目错了,应该是-5xy,不是-5y
x:y=2:3设x=2k,则y=3k∴x²+xy+2y²/x²-xy+y²=(4k²+6k²+9k²)/(4k²-6k&
已知xy+x+y=6则xy+x+y+1=(x+1)(y+1)=7=7×1因为x,y都是自然数(非负整数)所以x+1,y+1≥1所以只能x+1=7y+1=1即x=6,y=0或x+1=1,y+1=7即x=
XY/X+Y=2∴xy=2(x+y)3X-5xY+3Y/-X+3XY-Y=[3(x+y)-5xy]/[-(x+y)+3xy]=[3(x+y)-10(x+y)]/[-(x+y)+6(x+y)]=-7/5
由xy=x+y得y=x/(x-1)>2解不等式,若x>1,则x>2x-2x<2;若x<1,则x<2x-2,x>2,无解.所以x的范围为1<x<2.
x+y=5xy(2x-3xy+2y)/(x+2xy+y)=[2(x+y)-3xy]/[(x+y)+2xy]=(2×5xy-3xy)/(5xy+2xy)=7xy/7xy=1再问:若x+1/x=3,求(x