若多项式2(x²-3xy-y²﹚-﹙3mxy﹢y²﹚中不含xy项,则m=多少
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![若多项式2(x²-3xy-y²﹚-﹙3mxy﹢y²﹚中不含xy项,则m=多少](/uploads/image/z/1612193-41-3.jpg?t=%E8%8B%A5%E5%A4%9A%E9%A1%B9%E5%BC%8F2%EF%BC%88x%26%23178%3B%EF%BC%8D3xy%EF%BC%8Dy%26%23178%3B%EF%B9%9A%EF%BC%8D%EF%B9%993mxy%EF%B9%A2y%26%23178%3B%EF%B9%9A%E4%B8%AD%E4%B8%8D%E5%90%ABxy%E9%A1%B9%2C%E5%88%99m%3D%E5%A4%9A%E5%B0%91)
若多项式2(x²-3xy-y²﹚-﹙3mxy﹢y²﹚中不含xy项,则m=多少
若多项式2(x²-3xy-y²﹚-﹙3mxy﹢y²﹚中不含xy项,则m=多少
若多项式2(x²-3xy-y²﹚-﹙3mxy﹢y²﹚中不含xy项,则m=多少
2(x²-3xy-y²﹚-﹙3mxy﹢y²﹚
=2x²-6xy-2y²-3mxy-y²
=2x²-(6+3m)xy-3y²
因为不含xy项
所以 -(6+3m)=0
3m= -6
m= -2