(3x平方-xy-2y平方)-2(x平方+xy-y平方)怎么算

问题描述:

(3x平方-xy-2y平方)-2(x平方+xy-y平方)怎么算

(3x²-xy-2y²)-2(x²+xy-y²)
=3x²-xy-2y²-2x²-2xy+2y²
=x²-3xy

原式=x^2-3xy=x(x-3y)

(3x²-xy-2y²)-2(x²+xy-y²)
=3x²-xy-2y²-2x²-2xy+2y²
=x²-3xy