2x+5Y＝-8 3x-2y＝7

计算(x^8-x^7y+x^5y^3-x^4y^4+x^3y^5-x^y^7+y^8)(x^2+xy+y^2) 化简下列各式,并求值:3(x-y)²-7(x-y)+8(x-y)²+6(x-y) 其中x=2,y化简下列各式,并求值:3(x-y)²-7(x-y)+8(x-y)²+6(x-y)其中x=2,y＝5 (2x+y)²+(x+3y)(x-3y)-x(5x+8y)因式分解 [2(x-y)^5-8(x-y)^2(x+y)+6y(x-y)^2]÷2(x-y)^2[2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2]÷2(x-y)^2 ｛y＝3x-7｛5x+2y＝8｛x-2y＝3｛2y+x＝-1｛2y-x＝6｛2x+y＝8 已知X＝11Y,（X－2）*3＝Y,（X－4）*5＝Y,（X－6）*7＝Y,（X－8）*9＝Y ,求X、Y各是多少? x+y=1 5x-2y=8 3x-y=7 2x-y=3x表示y和用y表示x 先化简,再求值.2(x-2y)^2+8(x-2y)-3(2y-x)^2+5(2y-x),其中-x+2y=-3RT为什么-3(2y-x)^2＝3(x-2y)²? 18(x+y)^8(x-y)^7÷[3(x+y)^3(x-y)^3]^2 3(x-y)^2-7(x-y)+8(y-x)^2+6(y-x)合并同类项. 5(x-y)^2-(x-y)-8(x-y)^2-3(x-y) 化简:3(x-y)²-7(x-y)+ 2(x-y)²+5(x-y) 2(x-y)+3（x+y）2-5(x-y)-8（x+y）2-（x-y） x－y＝2 2x－3y＝7 求x求y 若｜x-y-5｜与｜2x+3y-15｜互为相反数,则x+y＝? 6x²y+2xy-3x²y²-7x-5yx-4y²x²-6x²y＝ 计算:1/(x-y)-1/(x+y)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8x^7/(x^8+y^8) 2x+5Y＝-8 3x-2y＝7