单项式-7x^2y,3x^2y^2z,-二分之一xy,5x^2y,0.5xy,-4x^3的和是( )A.五次三项式B.五次四项式C.三次多项式D.

（x+y+z）/3是不是单项式 单项式乘单项式 (11 20:52:59)2x=3,2y=6,2z=12,试证明2y=x+y 单项式2x^3y次数是( ) [3(x-y)^3-(y-x)^2+x-y]÷(x-y) 多项式除以单项式 试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) 已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z 2(x+y)(x+y-z)+3(y-z)(x+y-z) 1.（x+y-z)+(x-y+z)-(x-y-z) 2.2x-(3x-2y+3)-(5y-2) (x-3y+2z)(x+3y-2z) （x-2y+3z)(x+2y-3z) (2y-x-3z)(-x-2y-3z) 化简(x+Y)^2(y+z-x)(z+x-y)+(x-y)^2(x+y+z)(x+y-z) 计算题(x+y)^2(y+z-x)(z+x-y)+(x-y)^2(x+y+z)(x+y-z). 1、y-x/x²-y²2、(x-y)(y-z)(z-x)/(z-y)(y-x)(x-z) 化简(y-x)(z-x)/(x-2y+z)(x+y-2z)+（z-y)(x-y)/(x-2z+y)(y+z-2x)+(x-z)(y-z)/(y+z-2x)(x-2y+z) 计算:(y-x)(z-x)/(x-2y+z)(x+y-2z)+(z-y)(x-y)/(x+y-2z)(y+z-2x)+(x-z)(y-z)/(y+z-2x)(x-2y+z) 2(x+y-z)-3(x-y+z)-5(x+y-z)+6(x-y+z) 计算 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0