我想问问怎么把x^2+y^2-4x+2y-4=0,化简成这个式子：(x-2)^2+(y+1)^2=9的,

我想问问怎么把x^2+y^2-4x+2y-4=0,化简成这个式子：(x-2)^2+(y+1)^2=9的, 把4（x-y+1)+y(y-2x)因式分解 二元一次方程问问(1) 2y-X=1 (2) 4y-X=3 [4y（2x-y)-2x(2x-y)]÷（2x-y)怎么做 [(2X+Y)*(2X+Y)-Y(Y+4X)]/2X 怎么算? (x-y)^4·(x-y)-2(y-x)³·（y-x)²怎么算, 4x方y/(x-2y)(x+2y)怎么算[x方/x-2y]-4x方y/(x-2y)(x+2y)=? 求(3x^4+2x^2)/(x^2+1)的不定积分,然后我想问问这题的思路,怎么把分母划去,变为可以积分的形式 把(x+y),(x-y)个作为一个整体合并同类项1,7(x+y)-2(x+y)-4(x+y)+2(x+y)2,(x-y)²＋2(x-y)－(x-y)－2(x-y)² 化简:(2x-y-z)/(x-y)(x-z)+(2y-z-x)/(y-z)(y-x)+(2z-x-y)/(z-x)(z-y)化简:(2x-y-z)/(x-y)(x-z)+(2y-z-x)/(y-z)(y-x)+(2z-x-y)/(z-x)(z-y)我知道把分母化成一样的、但是之后怎么算? X^4-5X^2+4Y^4怎么变化成(X+Y)(X-Y)(X+2Y)(X-2Y)这步?就算是把(X+Y)(X-Y)(X+2Y)(X-2Y)算出来 也是=（X^2-Y^2)(X^2-4Y^2)=X^4-5X^2Y^2+4Y^4...也不是=(X^4-5X^2+4Y^4) 高数中偏导数的问题求函数Z=(X*X*Y*Y)/(X-Y）对自变量X的偏导数怎么做啊?书上是这么写的.将Y看成常数,对X求导,得【2X*Y*Y（X-Y）-X*X*Y*Y】/(X-Y)(X-Y)在化简一下就是【X*X*Y*Y-2X*Y*Y*Y】/(X-Y)(X-Y)我想问 把(x+3y)(3x-4y)-(x-2y)(x+3y)分解因式!答案是2(x+3y)(x-y) 我想问.上面的2个(x+3y)不是可以变成(x+3y)²为什么最后会变成(x+3y)的?指教指教下! 把16y-x^2y因式分解 [4x-(2x-y)]/(2x+y)(2x-y)怎么去分母? 2xy/(x+y)(x+y)与x/(x+y)(x-y)怎么通分 把下列各式因式分解 （1）、a^2(x-y)-4a(y-x)+4(x-y) (2)、(x+y)(x-y)-(x+z)(x-z) 把(x-y)看作一个整体,化解:5(x-y)+2(x-y)-4(x-y)= 3(x-y)把(x-y)看作一个整体,化解:5(x-y)+2(x-y)-4(x-y)=3(x-y)²-4(x-y)+7(x-y)-6(x-y)²=