(x+y)^2(x-y)^2-(x-y)(x+y)(x^2+y^2).已知a,b,c分别为三角形ABC的三条边长,你能用因式分解的知识说明b^2+c^2-a^2+2bc一定是正数吗?

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 化简y(x+y)+(x+y)(x-y)-x^2 (x+y)(x-y)-(x-y)^2如题 (x+y)(x-y)-(x-y)^2 【2(x-y)(x-y)(x-y)-8(x-y)(x-y)(x+y)+6y(x-y)(x-y)]/2(x-y)(x-y) 因式分解x(x+y)(x-y)-x(x+y)^2 [(x-y)^2-(x+2y)(x-2y)]/y 计算:y-x分之x+y+x-y分之y-y-x分之2x-y x^2(x-y)+(y-x) x(x-y)2-(y-x)3 【(x-y)^2+(x+y)(x-y)】除以 2x [(x-y)²+(x+y)(x-y)]除以2x [2/3x-2/x+y(x+y/3x-x-y)]/x-y/x 化简：{2/3x-2/(x+y)[(x+y)/3x-x-y]}/(x+y)/x 计算2/3x-2/x+y(x+y/3x-x-y)/x-y/x 化简3x-2/(x+y)[(x+y)/3x-x-y]÷(x-y)/x 化简：[(x+y)(x-y)(x+y)^2-2y(x-2y)](-2y) 谢谢! 计算：[(x+y)(x-y)-(x-y)^2+2y(x-y)]/(-2y) [(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y