2x(x-y)四次方-x²(x-y)²+xy(y-x)²=2x(x-y)四次方-x²(x-y)²+xy(x-y)²=x(x-y)²[2(x-y)²-x+y]=x(x-y)²[2(x-y)²-(x-y)]=x(x-y)³(2x-2y-1)又是你 0 0 好强悍!!对了问一下上一题那个m²≥180怎么解mm≤-√180，m≥√180