问题
填空题
计算:2-22-23-…-218-219+220=______.
答案
设S=-22-23-…-218-219①,
则2S=-23-…-218-219-220②,
②-①得S=-220+4,
∴2-22-23-…-218-219+220=2+S+220,
=2+4-220+220,
=6.
故答案为:6.
计算:2-22-23-…-218-219+220=______.
设S=-22-23-…-218-219①,
则2S=-23-…-218-219-220②,
②-①得S=-220+4,
∴2-22-23-…-218-219+220=2+S+220,
=2+4-220+220,
=6.
故答案为:6.