-1\4x^2+1\3xy-1\9y^2

问题描述:

-1\4x^2+1\3xy-1\9y^2

-1\4x^2+1\3xy-1\9y^2
=-(1/4x²-1/3xy+1/9y²)
=-(1/2x-1/3y)²