Question

 bài1 :tính nhanh
1997.2003
 

Answer 1

\(1997.2003=\left(2000-3\right)\left(2000+3\right)=2000^2-3^2=4000000-9=3999991\)

Answer 2

\(1997\cdot2003=\left(2000-3\right)\left(2000+3\right)=3999991\)