Question

9992－1000×998 用平方差公式计算

999的2次方－1000×998

Answer 1

999的2次方-1000×998
=999的2次方-1-1000×998+1
=(999+1)(999-1)-1000×998+1
=1000×998-1000×998+1
=1

Answer 2

999²-1000×998
=(1000-1)²-1000×(1000-2)
=(1000-1)²-1000²+2000
=[(1000-1)+1000][(1000-1)-1000]+2000
=(1999)(-1)+2000
=-1999+2000
=1