计算2x-5y=3 3x-5y=4

两个式子作差得到x=5带入得到y=23

3x+2=y和11x=y,得到x=1/4,y=11/4,5X+4=Y和7X+6=Y,得到X=-1,Y=-1代入9X+8=y,不成立,方程组无解..

-x^y^7+y^8)(这里有问题,x的几次方?再问：就是一次方再答：(x^8-x^7y+x^5y^3-x^4y^4+x^3y^5-xy^7+y^8)(x^2+xy+y^2)=（x^8-x^7y+x^

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

40x=2x25y40x=50yy=5/4xx+y=36x+5/4x=369/4x=36x=16y=16x5/4=202x+3y=15.54x+6y=315x+6y-4x-6y=35-31x=42x4

1.(5x+y)(3x-5y)-(4x-y)(4y+x)=15x²-25xy+3xy-5y²-(16xy+4x²-4y²-xy)=15x²-22xy-

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+

原式=(x''+9xy+20y'')(x''-y'')带入数据得：(64/9-72/7+180/49)*(64/9-9/49)再通分=((3136-4536+1260)/441)*(3136-81)/

10再答：x=2.y=-3.z=2所以2+3+5=10再问：再答：那个给点给点财富值吗

x-y/5y=(x-y)(x-y)/(5y(x-y))=(y-x)^2/(5y(x-y))

用1、2式求出x与y的关系（用y表示x）,代入1、3式,可以求出y,也就可以求出x1、2式求得：20x=-6y,即：x=-3y/10代入1、3式,得到y=10/51,则x=-1/17

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

5(x+y)(x-y)-2(x+y)^2+3(x-y)^2=3(x-y)^2+5(x+y)(x-y)-2(x+y)^2=(3(x-y)-(x+y))(3(x-y)+2(x+y))=(2x-4y)(5x

3x-2y-5x+7y-1,其中x=-1/2,y=-1=-2x+5y-1=-2×(-1/2)+5×(-1)-1=1-5-1=-5;很高兴为您解答,skyhunter002为您答疑解惑如果本题有什么不明

=((x+y)-(x-y))*((x+y)-3(x-y))=2y*(4y-2x)=4y*(2y-x)带入得到=4*-0.8*(-1.6-5)=4*0.8*6.6=21.12

解(x-y)(x+y)-(x-2y)²+x(3x-5y)-(x-y)(x-2y)=(x²-y²)-(x²-4xy+4y²)+(3x²-5xy

2y=5x-3代入得3x-2(5x-3)=-1x=1y=1a=1/3b-12b-5/3b+5=1b=-12a=-52、把x=1y=3和x=2y=3分别代入方程3=k+b3=2k+bk=0b=33、把x

[(x-y)^3]^m[(x-y)^m]^5=[(x-y)^m]^3[(x-y)^m]^5=[(x-y)^m]^（3+5）=(x-y)^m]^8

(x+2y)(x-2y)-(x+2y)-(x-2y)(2y-x)=x^2-4y^2-x-2y+(x^2-4xy+4y^2)=x^2-4y^2-x-2y+x^2-4xy+4y^2=2x^2-x-2y-4

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