1.设u=x-2y,v=x+2y,则原式=6u^2v-7uv+2v^3,非齐次,无法分解,
若改为原式=6u^2v-7uv^2+2v^3,则
原式=v(6u^2-7uv+2v^2)=v(3u-2v)(2u-v)
=(x+2y)[3(x-2y)-2(x+2y)][2(x-2y)-(x+2y)]
=(x+2y)(x-10y)(x-6y).
2.设x=m-n,则原式=x^3-5nx^2+6xn^2=x(x^2-5nx+6n^2)=x(x-2n)(x-3n)
=(m-n)(m-3n)(m-4n).