Question

Dati factor comun
1. 1992 + 1993 × 1992 - 1994 × 1991 =
2. 1996 × 1995 - 1995 x 1994 - 2 x 1994 =
3. 999 + 999 × 999 + 1000 =

Answer 1

1.1992+1993•1992-1994•1991=
   1992(1+1993)-1994•1991=
    1992•1994-1994•1991=
     1994(1992-1991) =1994

2.1996•1995-1995•1994-2•1994=
 1995(1996-1994)-2•1994=
  1995•2-2•1994=
   2(1995-1994)= 2

3.999+999•999+1000=
   999(1+999)+1000=
   999•1000+1000=
   1000(999+1)=
    1000•1000 = 1000000