-x-7y-1 3[7y-2]

1.x=1y=1.72.2983.248189

8（x平方-2y平方)-x(7x+y)+xy=8x平方-16y平方-7x平方-xy+xy=x平方-4y平方=(x-2y)(x+2y)手机提问的朋友在客户端右上角评价点【满意】即可.再问：太棒了！连我这

-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^

2(y-x)²-7(x-y)+6(x-y)-3(y-x)²=-(y-x)²-(x-y)=-(x-y)²-(x-y)=-(x-y)[(x-y)+1]=(y-x)(

根号(x+y-8)+根号(8-x-y)=根号(3x-y-4)+根号(x-2y+7),根据二次根式有意义得：X+Y-8≥0,8-X-Y≥0,∴X+Y≥8,X+Y≤8,∴X+Y=8,左边为0,右边两个非负

x^2-10x-11=(x-10)(x+1)x^2y^2-16xy+60=(xy-10)(xy-6)(x+y)^2-7(x+y)-18=(x+y-9)(x+y+2)x^2-13xy-30y^2=(x-

6X+5Y=312X+3Y=17由6X+5Y=31得X=（31-5Y）/6再将X代入第二个式子得到Y=5然后可知X=1则6x-2y+y-y=6x-2y=6*1-2*5=6-10=-4再问：x=1怎么算

2x+y+z=10(1)x+2y+z=-6(2)x+y+z=8(3)(2)-(3):y=-14(4)(1)-(2):x-y=16(5)把（4）代入（5）：x+14=16x=2(6)把（4）和（6）代入

(x-y)^8

第一题：（x-y)/13=y/713y=7x-7y20y=7xx/y=20/7两边都加1（x+y)/y=27/7第二题：x/6=y/4=z/3（x,y,z,不为零）用特值法令x/6=y/4=z/3=1

(x-y)^2+7(x+y)-11(x-y)^2-8(x+y),=-10(x-y)²-(x+y)当x+y=-3,x-y=-1时=-10*(-1)²-(-3)=-10+3=-7

x=-2.5y=-3再问：过程再答：2x+y/3-2y=0①2(2x+y)-5=7y②展开②式，4x+2y-5=7y，移项整理的得4x-5y=5③将①整理得2x-5y/3=0④将④×2得4x-10y/

1/(x-y)-1/(x+y)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8y^7/(x^8+y^8)=【（x+y)-(x-y)】/(x-y)(x+y)-2y/(x^2+y^2)-4y^

若(x-y)/(x+y)=3那么x-y=3(x+y)x-y=3x+3y故x=-2y所以(x+2y)/(6x-7y)=(-2y+2y)/(6*(-2y)-7y)=0如果不懂,请Hi我,祝学习愉快!

(-3x+7y)(-7y-3x)-(x-3y)(2x+3y)=(3x-7y)(3x+7y)+(3y-x)(3y+2x)后半部分相当于(x+a)(x+b)=x^2+(a+b)x+ab=9x^2-49y^

1、(-7x^y)(2x^y-3xy^3+xy)=-14x^(2y)+21x^(y+1)y^3-7x^(y+1)y;2、((x-y)^6)/((y-x)^3)/(x-y)=-(x-y)^3/(x-y)

(x-y)^7÷(y-x)^6+(-x-y)^3÷(x+y)^2=(x-y)^7÷(x-y)^6+[-(x+y)^3]÷(x+y)^2=(x-y)+[-(x+y)]=x-y-x-y=-2y

等于.-3y-10x

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+y)(x-y-x+2y)/y=(x+y)y/y=x+y因为已知代数式无意义,即：0的0次方无意义,所以3x-2y-7=0及2x+3y+4=0,解得：x=1,y=-2代入x+y=-1