Question

计算:2-2^2-2^3-2^4-……-2^19+2^20

Answer 1

2-2^2-2^3-2^4-……-2^19+2^20

=2-2^2-2^3-2^4-……+(-2^19+2^20)

=2-2^2-2^3-2^4-……+2^19

=2+2^2

=6