Tính: C= 3+3^3+3^3+...+3^1000

C=3+32+33+...+31000

3C=3.3+32.3+33.3+...+31000.3

3C=32+33+34+...+31001

3C−C=32+33+34+...+31001−3+32+33+...+31000

2C=32+33+34+...+31001−3−32−33−...−31000

2C=31001−3

C=31001−32