5x-2y=3,x 6y=23的消元
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方程组一式加二倍的二式,得X=2m–1带入二式,Y=–2m4,再带入不等式,剩下的自己算吧再问:答案是多少?验算一下再答:x+2Y=2m-1+2(-2m+4)7/2
再问:谢谢,再答:不言谢!
[(x+2y)^2-(x+y)(3x-y)-5y^2]/2x=(x^2+4xy+4y^2-3x^2-3xy+xy+y^2-5y^2)/2x=(-2x^2+2xy)/2x=-x+y=2+1/2=二分之五
设x-y=mx+y=n则6m-2n=143m+n=5解得m=2n=-1即x-y=2x+y=-1解得x=1/2y=-3/2
5x-2y=x-y=4x-3y-2则4x=y代入:x-4x=4x-12x-2得到x=-2/5y=-8/5
[(3x+2y)(3x-2y)-(x+2y)(5x-2y)]÷8x=(9x^2-4y^2-5x^2+2xy-10xy+4y^2)/(8x)=(4x^2-8xy)/(8x)=(x-2y)/2=2012/
化简得:-x+7y=11①7x+3y=27②①式×7得:-7x+49y=77③②+③得:52y=104∴y=2代入①得:x=3∴x=3,y=2再问:亲,是代入法哦!再答:代入法①式得3x+3y-4x+
【(x+2y)²-(x+y)(3x-y)-5y²】÷2x=y-x=0.5+2=2.5
2X^2+23XY-19Y^2^2表示平方.
∵|2x-y+5|+(x+2y-4)的平方=0∴2x-y+5=0,x+2y-4=0∴2x-y=-5,x+2y=4x-3y=-9则(2x-y)的三次方-(x-3y)(y-2x)的平方=(-5)^3-(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
2X-4Y=6(1)3X+2Y=17(2)(1)+(2)*22X+3X*2-4Y+2Y*2=6+17*28X=40X=5Y=6-2*5/(-4)=13Y=X+5(1)2X+5X=23(2)(题目可能有
2y=x-3带入[(3x+2y)(3x-2y)-(x+2y)(5x-2y)]/4x=[(3x+x-3)(3X-x+3)-(x+x-3)(5x+3-x)]/4x=(8x2-6x=12x-9-8x2=12
原式=(9x²-4y²-5x²-8xy+4y²)÷4x=(4x²-8xy)÷4x=x-2y=2011
若x-y/x+y=5则x-y=5(x+y)所以求x-y/2x+2y+5x+5y/3x-3y=5(x+y)/[2(x+y)]+5(x+y)/3(x-y)=5/2+5(x+y)/[3*5(x+y)]=5/
解(x-y)(x+y)-(x-2y)²+x(3x-5y)-(x-y)(x-2y)=(x²-y²)-(x²-4xy+4y²)+(3x²-5xy
5x=3y,x=3y/5(2x+y)的平方=5x(x+y)+94x²+4xy+y²=5x²+5xy+9x²+xy-y²+9=09y²/25+
3x-2y5=x+y3交叉相乘,乘积相等:5(x+y)=3(3x-2y)5x+5y=9x-6y11y=4x4x=11y那么x:y=11:4
X/Y=5/3,求X/(X+Y)+X/(X-Y)-Y^2/(X^2-Y^2)=1/[1+(X/Y)]+1/[1-(X/Y)]-1/[(X^2/Y^2)-1]=1/[1+5/3]+1/[1-5/3]-1
【(x+2y)2-(x+y)(3x-y)-5y2】÷(2x)=[x^2+4xy+y^2-(3x^2+2xy-y^2)-5y^2]/(2x)=[-2x^2+2xy]/(2x)=y-x=1/2-2=-3/