4X加3Y=5,X-2Y=4,用加减消元法解方程组
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原式=(9x²+24xy+16y²-4x²+y²-5x²+6xy-y²)÷(-2y)=(30xy+16y²)÷(-2y)=-15x
原式=(x+2y)^2-(x+2y)+1/4=0则x+2y=1/2
由于根号下必须是大于等于零,则有:x-3>=0.3-x>=0得x>=3.x
(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
由(1)得3x+3y+2x-2y=365x+y=36(3)由(2)得4x+4y-3x+3y=-20x+7y=-20(4)(3)×7-(4)得34x=272∴x=8把x=8代入(3)得y=-4∴x=8y
由于√x²-4与√4-x²都要成立则x²-4=0所以x=2或者-2由于1/x-2成立则x≠2所以x=-2y=1/(-2-2)=-1/4所以3x+4y=3*(-2)+4*(
{(x+y)/2+(x-y)/3=63(x+y)+2(x-y)=36(1)4(x+y)-3(x-y)=-20(2)由(1)*3+(2)*2得9(x+y)+6(x-y)+8(x+y)-6(x-y)=36
3x+2y=2m+5(1)2x-y=4(2)x+y=5(3)由题意,满足(2)(3)同样满足(1)(2)+(3)3x=9x=3,y=2代入(1)3*3+2*2=2m+513=2m+5m=4
x=-20/7y=-16/21再问:3x-4等于5,2x加3y等于负8第一题第二题3x加2x=5x加2,2(3x加2y)等于2x加8再答:加题就要加分数,我很忙的,不然太吃亏了再问:你看错了把,这是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+
4(x+y)-3(x-y)=14x+7y=14(x+y)/2+(x-y)/3=6两边同乘以6,得3(x+y)+2(x-y)=365x+y=36则x+7(36-5x)=14x=7,y=1
楼上的全错,{(3x+y)(3x-y)-(x-5y)(5x-y)-(x-2y)²}÷(-4x)={9X²-(5x²-xy-25x²+5y²)-(x&s
2分之2x+y加3分之2x-y=1,——》10x+y=6,.(1)4*(2x+y)-5(2x-y)=8,——》9y-2x=8,.(2)(1)+(2)*5,得:46y=46,即y=1,代入(1),得:x
x^2+16y^2+4x+4y+5=0x^2+4x+4+4y^2+4y+1=0(x+2)^2+(2y+1)^2=0因为x^2>=0所以x+2=02y+1=0所以x=-2y=-1/2
第二个方程是不是写错了2/(x+y)+3/(x-y)=6是这样吗
3(x+y)-4(x-y)=4(x+y)/2+(x-y)/6=1令a=x+y,b=x-y3a-4b=4(1)a/2+b/6=1则3a+b=6(2)(2)-(1)5b=2b=2/5a=(6-b)/3=2
(5x+3y)(3y-5x)-(4x-y)(4y+x)=(3y)^2-(5x)^2-(4x^2+15xy-4y^2)=9y^2-25x^2-4x^2-15xy+4y^2=13y^2-15xy-29x^
依题意可知在根号下的1-3y和3y-1都有意义故1-3y〉=0且3y-1〉=0所以y=1/3x=26y-4x=-6
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
我把方法告诉你,最后的答案你自己做吧,很容易.(x+y)(x+2y)(x+3y)(x+4y)=-40(x+y)(x+4y)(x+2y)(x+3y)=-40(x^2+5yx+44)(x^2+5yx+66