2x-5y=-21 4x 3y 23用加减消元法解析
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原式=(9x²+24xy+16y²-4x²+y²-5x²+6xy-y²)÷(-2y)=(30xy+16y²)÷(-2y)=-15x
(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=4x-2y-z-5x[6y-(x+y)]+x-(3y-10z)=4x-2y-z-30xy+5x²+5xy+x-3
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
解13x-2y=9x-3y=2将式2左右两边同时乘以3得3x-9y=6与式1相减有-9y+2y=6-9解得y=3/7代入代2有x-3*3/7=2解得x=23/7故x=23/7y=3/7解2x+y=5x
x=5y=-2
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+
楼上的全错,{(3x+y)(3x-y)-(x-5y)(5x-y)-(x-2y)²}÷(-4x)={9X²-(5x²-xy-25x²+5y²)-(x&s
(x*x+y*y)(x*x+y*y)-4x*x*y*y=(x^4-2x^2y^2+y^4)=(x^2-y^2)^2=0x^2=y^2x/y=±1(x*x+5xy+y*y)/(x*x+2xy+y*y)=
x-y/5y=(x-y)(x-y)/(5y(x-y))=(y-x)^2/(5y(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
X^2表示平方X^2+4X+4+Y^2-2Y+1=0(X+2)^2+(Y-1)^2=0因为平方大于=0所以X+2=0Y-1=0X=-2Y=1X^2+Y^2=5
3x-5y=0,则x+y/x=(8/5),x-y/y=(2/3),2x-3y/2x+3y=(1/19)因为3x-5y=0所以3x=5y设x=5,y=3,可以解得3x-5y=0,则x+y/x=(8/5)
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+
再答:再答:看后面这个图再答:不懂可以问我
1,-3再问:过程。。。再答:★(x²-2x)+(y²-4y)=5★(x-1)²+(y-2)²=1+4-5★(x-l)²=0,(y-2)²=
展开x^2-2y^2-xy=-5x^2-2y^2+xy=7所以x^2-2y^2=1xy=6上式除以下式,解分式方程x/y=3/2或-4/3(舍去)所以x^2=9y^2=4x=3y=2或x=-3y=-2
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