1+2-3-4+5+6-7-8+9+10-11-12+13+......+1990-1991-1992+1993

2024-12-05 06:27:10
推荐回答(2个)
回答1:

=(1-3)+(2-4)+(5-7)+(6-8)+……+(1989-1991)+(1990-1992)+1993 共1992/2=996组
=(-2)+(-2)+(-2)+(-2)+……+(-2)+(-2)+1993 共996组-2
=-2×996+1993
=-1992+1993
=1

回答2:

1+2-3-4+5+6-7-8+9+10-11-12+.......+1990
=1+(2-3-4+5+6-7-8+9+10-11-12+.......+1989)+1990
=1+[(2-3-4+5)+(6-7-8+9)+(10-11-12+13)+.......+(1986-1987-1988+1989)+(1990-1991-1992+1993)]
=1+0
=1