若2x 5y 4z=0,3x y -7z =4
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x/2=y/3x=2y/3所以x²-2xy-3y²/x²-6xy-7y²=(x+y)(x-3y)/(x+y)(x-7y)=(x-3y)/(x-7y)=(2y/3
A+B-3C=08x²y-6xy²-3xy+7xy²-2xy+5x²y-3C=0(13x²y-5xy+xy²)/3=CC-A=(13x&su
1.2(Xy+Xy)-3(Xy-xy)-4Xy=2*2xy-0-4xy=4xy-4xy=02.1/2ab-5aC-(3acb)+(3aC-4aC)=1/2ab-5ac-3acb-ac=1/2ab-6a
2x+3y-3xy+(4xy-3x)-(4y-7)=2x+3y-3xy+4xy-3x-4y+7=-x-y+xy+7=-6-6+2+7=-3
把c用ab表示出来.然后在减a.就是简单的运算.
∵A+B-C=0∴A+B=C将A和B的值代入A+B=C中即可求出C的值.步骤:∵A+B-C=0∴A+B=C又∵A=8x二次方y-6xy二次方-3xy,B=7xy二次方-2xy+5x二次方y∴C=………
解(x+1)平方+/y-1/=0∴x+1=0,y-1=0∴x=-1,y=1∴2(xy-5xy平方)-(3xy平方-xy)=(2xy+xy)+(-10xy平方-3xy平方)=3xy-13xy平方=3×(
根据题意得:x+y=02y-1=0,解得:x=-12y=12.则xy-[2xy-3(xy-1)]=xy-[2xy-3xy+3]=xy-2xy+3xy-3=2xy-3=2×(-12)×12-3=-312
1、x-2√xy-3y=(√x-3√y)(√x+√y)=0解得√x=3√y或者√x=-√y(舍去)也就是x=9y2x+y+√xy除以y-x-√xy=(2*9y+y+3√y*√y)/(y-9y-3√y*
3x²+3xy=03x²=-3xy因为x不等于0所以x=-y所以x:y=1:-1
(3xy+2)^2+|7-x-y|=0,则3xy+2=0,7-x-y=0,即x+y=7,xy=-2/3(5xy+10y)-[-5x-(4xy-2y+3x)]=5xy+10y-(-5x-4xy+2y-3
A=8x的二次方乘以y-6xy的二次方-3xyB=7xy的二次方-2xy+5x的二次方乘以yA+B=13x的二次方乘以y+xy的二次方-5xy=3CC=(13x的二次方乘以y+xy的二次方-5xy)/
(3x^2+2xy)/xy-(2x^2-xy)/xy=(3x^2+2xy-2x^2+xy)/xy=(x^2+3xy)/xy=x(x+3y)/xy=(x+3y)/y
解C=(-A-B)/2=-2x^2y+xy-2xy^2C-A=-7x^2y-3xy+xy^2
x+2y=0x=-2yxy+y^2分之x^2+3xy=x^2+3xy/xy+y^2=4y^2-6y^2/-2y^2+y^2=-2y^2/-y^2=2
x^2+2xy-3y^2=0x^2+2xy+y^2-4y^2=0(x+y)^2=4y^2x+y=2y或x+y=-2yx=y或x=-3y因为两个正实数所以x=yx^2+xy+y^2/x^2-xy+y^2
A=5x^2y-3xy^2+4xyB=7xy^2-2xy+x^2y2C=-A-B2C-2A=-3A-B=-15x^2y+9xy^2-12xy-7xy^2+2xy-x^2y=-16x^2y+2xy^2-
x²-3xy+4x=3,y²+xy-4y+7=0相加得x²-2xy+y²+4(x-y)+4=0(x-y)²+4(x-y)+4=0(x-y+2)=0,得
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
x²+y²=7转成x²=7-y²将xy=-2和x²=7-y²代人(5x²-3xy-4y²-11xy-7x²+2