解一:3a(6a+3)(6a-3),当a=-2/3时.代入得:3*(-2/3)*[6*(-2/3)+3]*[6*(-2/3)-3]=-2*(-1)*(-7)=-14解二:[(2x-y)^2-(3x+y)(3x-y)+5x(x-y)]÷(-y)=[(4x^2-4xy+y^2)-(9x^2-y^2)+5x^2-5xy)]÷(-y)=[4x^2-9x^2+5x^2+y^2+y^2-...