原式=512
12-22+32-42+……-1002+1012
=12+(32-22) ×(1012-12)÷(10×2)
=12+10×1000÷20
=12+500
=512
计算过程如下:
12-22+32-42+52-62+…-1002+1012
=(12+32+52+…+1012)-(22+42+62+…+1002)
=(12+1012)÷2×[(1012-12)÷20+1]-(22+1002)÷2×[(1002-22)÷20+1]
=512×51-521×50
=512×(51-50)
=512