8x-3=y7x 4=y的解-搜答案-拍题作业网

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！

2x+3y=101将y=-6代入3得：x=14x+y=82将x=14,y=-6代入3x+5y=m+2得由2得,x=8-y33x14+5x(-6)=m+2将3代入1式得：所以m=102(8-y)+3y=

5x-2y=x-y=4x-3y-2则4x=y代入：x-4x=4x-12x-2得到x=-2/5y=-8/5

x+y/3+x-y/2=63(x+y)-2(x-y)=282x+2y+3x-3y=363x+3y-2x+2y=285x-y=36x+5y=285x-y=365x+25y=14026y=104y=4x=

[(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/

3x+y=k①x+3y=2②②乘以3,得3x+9y=6③③减去①,得8y=6-ky=(6-k)/8将y=(6-k)/8代入②中,得x+3(6-k)/8=2x=2-3(6-k)/8因为x,y

合并同类项后8x+2y+3=8x+2y+3=8x=2y+3可以看出最后等于0,随意整个等式为0,x=0,y=-3/2

可以得出x.x+y.y-6x-8y+25=x.x-6x+9+y.y-8y+16=(x-3).(x-3)+(y-4).(y-4)=0因为(x-3).(x-3)>=0,(y-4).(y-4)>=0所以x=

X=1,Y=1

y'sin(y/x)-y/x*sin(y/x)+1=0令y/x=u,则y'=u+xu'所以(u+xu')sinu-usinu+1=0xu'sinu+1=0-sinudu=dx/x两边积分：cosu=l

x-y=a+32x+y=53x=a+8x=(a+8)/3>0a>-8y=-(2a+1)/3-1/2所以a>-1/2

{{x-y)/3-(x+y)/4=2①{(x-y)/6-(x+y)/8=3②②×2得：(x-y)/3-(x+y)/4=6③①与③矛盾∴原方程组无解

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

解题过程如下..已知2x-y=73x+y=8则2x-y+3x+y=7+8=15即5x=15x=3将x=3代入2x-y=7即6-y=7得y=-1

答：3(x+y)²-7(x+y)+8(x+y)²+6(x+y)-11(x+y)²=(3+8-11)(x+y)²+(6-7)(x+y)=0-(x+y)=-x-y

【(x-y)的3次方-8(x-y)的2次方(x+y)+6y(x-y)的平方】/2(x-y)的平方=(x-y)²[x-y-8(x+y)+6y]/2(x-y)²=1/2（x-y-8x-

绝对值项恒非负,两绝对值项之和=0,两绝对值项分别=03x-y=0(1)x+y=0(2)(1)+(2)4x=0x=0,代入(2)y=-x=0(x-y)/(xy)无意义,因此题目错了.

因为8/(x+y)+18/(x-y)=4/3,两边乘以3得24/(x+y)+54/(x-y)=4两边同时减去24/(x+y)+24/(x-y)=7/3得30/(x-y)=5/3所以x-y=18代入8/

很累-3x-2y