A=1-2+22-23+...+21006
2A=2-22+23-24+...+21007
2A-A=(2-22+23-24+...+21007)-(1-2+22-23+...+21006)
=21007-1.Vậy A =21007-1
B=3-32+33-34+...+32000
3B=32-33+34-35+...+32001
3B-B=(32-33+34-35+...+32001)-(3-32+33-34+...+32000)
2B=32001-3.Vậy:\(B=\dfrac{3^{2001}-3}{2}\)