化简:(1):4m-7n-2(m-2n).(2):-(x²-2xy-y²)+95x²-2xy-3y²).
问题描述:
化简:(1):4m-7n-2(m-2n).(2):-(x²-2xy-y²)+95x²-2xy-3y²).
答
4m-7n-2(m-2n)
=4m-7n-2m+4n
=2m-3n
-(x²-2xy-y²)+(5x²-2xy-3y²)
=-x²+2xy+y²+5x²-2xy-3y²
=4x²-2y²