2004.05x1997.05减2001.05x1999.一定要详细,还有说明每一步的原因.
问题描述：
2004.05x1997.05减2001.05x1999.一定要详细,还有说明每一步的原因.
答
2004.05x1997.05-2001.05x1999.05
=(2000.55+3.5)(2000.55-3.5)-(2000.55+1.5)(2000.55-1.5)
=2000.55²-3.5²-(2000.55²-1.5²)
=2000.55²-3.5²-2000.55²+1.5²
=1.5²-3.5²
=(1.5+3.5)(1.5-3.5)
=5×(-2)
=-10