Ta có: 2E= 2+2^2+2^3+2^4+...+2^10
2E - E = (2+2^2+2^3+2^4+...+2^10) - (1+2+2^2+2^3+...+2^9)
E = 2^10-1
\(E=1+2+2^2+2^3+...+2^9\)
=>\(2E=2+2^2+2^3+2^4+...+2^{10}\)
=>\(2E-E=\left(2+2^2+2^3+2^4+...+2^{10}\right)-\left(1+2+2^2+2^3+...+2^9\right)\)
=>\(E=2^{10}-1=1024-1=1023\)