7(x-1)2+4(x-1)(y+2)-20(y+2)2 8x2y2+6xy-35 2(a+b)2+(a+b)(a-b)-6(a-b)27（x-1）²+4（x-1）（y+2）-20（y+2）²8x²y²+6xy-352(a+b)²+(a+b)(a-b)-6(a-b)²

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 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) x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 -(5x+y)-7(x-y) -2分之1（x+y）+4分之1（x+2y） 4x-2（x-2） -2x-（3x-1） x-(5x-2y)+2(2x-y) x+2y=2x+y+1=7x-y 求：2x-y? (2x-7y)(3x+4y-1) (2x-7y)(3x+4y-1) 4x-2y+x+7y-1 合成同类项 因式分解：-1/2*x*x*x*y+1/4*x*x*y*y-1/8*x*x*x*y*y*y {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 把(x-y)看作一个整体,化简:(1)5(x-y)+2(x-y)-4(x-y);(2)3(x-y²-4(x-y)+7（x-y)-6(x-y) 因式分解(x-1)(3x-7y)^2+4(1-x)(x+y)^2 (2X-Y)-2(3X-1/2Y) 6(X/3+X-1/2) (X-3)-(5X+7) -4X-(-(3/1X)+(-1/4X) - 1/(x-y)+1/(x+y)+2x/(x^2+y^2)+4x^3/(x^4+y^4)化简 化简：[(2x-y)平方+（2x+y)(2x-y)-4x(x-y+1)]÷2x 初二上学期方程题 4x+y=5 5x+4y=63x-2y=1 2x+3y=13x-2y=7 7x+5y=32x+3y=17 2x-y=-4x+5y=6 2x+y=23x-6y=4 3x+2y=52x+y=73x-4y=53x+y=1x-2y=-1x+y=42x+3y=92x-3y=74x+5y=3x+y=20004x+6y=90003x+5y=113x-2y=42x+3y=215x-2y=5x+y=54x+3y=182x+3y=16x+4y=132x+3y=40x