已知圆(x-1)^2 y^2=3 4的一切线y=kx与

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已知圆(x-1)^2 y^2=3 4的一切线y=kx与
已知x=3分之1,y=二分之一,求代数式x-(x+y)+(x+2y)-(x+3y)+...-(x+13y)的值

x=1/3y=1/2x-(x+y)+(x+2y)-(x+3y)+...-(x+13y)=6y-13y=-7y=-7/2=-3.5

已知|2x-3y|+|3x-y-1|=0,求x,y的值.

2x-3y=0(1)3x-y-1=0(2)由(2)得y=3x-1(3)把y=3x-1代入(1)得2x-9x+3=0∴x=3/7把x=3/7代入(3)得y=2/7∴x=3/7y=2/7

已知x-y=-3y+5,则式子x+2y-1的值是?

把x-y=-3y+5的左边移到右边:x-y+3y-5=0所以:x+2y-5=0x+2y-1=4

已知函数y=log1/2[(3-x)(1-x)]

如果楼主说的是1/2为底数的话令f(x)=(3-x)(1-x)则f(x)=x^2-4x+3=(x-2)^2-1所以f(x)的值域是[0,正无穷)因此log1/2[(3-x)(1-x)]的值域是(负无穷

已知:3x=8y.求(1)x+y/y (2)2x+3y/x-2y

3x=8yx/y=8/3(1)x+y/y=x/y+1=8/3+1=11/3(2)2x+3y/x-2y分子分母同时除以y得=(2x/y+3)/(x/y-2)=(16/3+3)/(8/3-2)=(25/3

已知3x-4y/2x+y=1/2 求x/y的值

3x-4y/2x+y=1/26x-8y=2x+y4x=9yx/y=9/4

已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y

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

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)

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

已知有理数x,y满足1/2|x-y|+|y-1/2|=0 求3x+7y

1/2|x-y|+|y-1/2|=0x-y=0y-1/2=0解得:x=y=1/23x+7y=10x=5

已知集合A={(x,y)| (y-3)/ (x-1)=2,x,y∈R},B={(x,y)| 4x+ay=16,x,y∈

∵(y-3)/(x-1)=2,x≠1,可化为y-2x=1,∵A∩B=空集,∴y-2x=1方程组无解ay+4x=16∴1/a=-2/4≠1/16解得a=-2又x≠1,则y≠3,∴3a+4≠16,a≠4当

已知1/x+1/y=5,求2x-3y+2y/-x+2xy-y

1/x+1/y=(x+y)/xy=5x+y=5xy2x-3xy+2y/-x+2xy-y=[2(x+y)-3xy]/[2xy-(x+y)]=(10xy-3xy)/(2x-5xy)=7xy/(-3xy)=

已知x=2y-1/3y-1,用含x的代数式表示y

3xy-x=2y-1;(3x-2)y=x-1;y=(x-1)/(3x-2);

已知4x=9y求(1)x+y/y (2)y-x/2x

4x=9yx=9/4*y(1)(x+y)/y=[(9/4)y+y]/y=(9/4+1)y/y=9/4+1=13/4(2)(y-x)/2x=[y-(9/4)y]/[2*(9/4)y]=(1-9/4)y/

已知x=2+根号3,y=2-根号3,计算代数式(x+y/x-y-x-y/x+y)乘以(1/x^2-1/y^2)

即xy=2²-(√3)=4-3=1原式=[(x+y)²-(x-y)²]/(x+y)(x-y)*[-(x²-y²)/x²y²]=(x

已知变量x,y满足约束条件x+2y-3=0,y-1

约束条件x+2y-3<=0,x+3y-3>=0,y-1<=0可行域为三角形ABC及其内部区域A(3,0),B(1,1),C(0,1)目标函数:z=ax+by令z=0得到初值线l0:a

已知:x,y满足|2x-y|+|y-1/2|=0,求7x-3y的值.

由已知得:2x-y=0y-1/2=0解得:x=1/4y=1/2所以原式=7/4-3/2=1/4

已知X和Y满足3X+4Y=2,X-Y-1/7

3X+4Y=23X=2-4YX=(2-4Y)/3X-Y-1/7D

已知X-Y=3,求X-Y的2次幂减3X+3Y+1

原式=(x-y)²-3(x-y)+1=3²-3×3+1x-y用3代替=1再问:3X+3Y是怎么转化成这个的3(X-Y),什么理由再答:是-3x+3y不是3x+3y

已知1/x+1/y=5,求(2x-3y+2y)/(x+2xy+y)的值

题目是否抄错?应该是(2X-3XY+2Y)/(X+2XY+Y)吧?1/X+1/Y=5(Y+X)/XY=5X+Y=5XY(2X-3XY+2Y)/(X+2XY+Y)=〔2(X+Y)-3XY〕/(X+Y+2

已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-(

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