Đáp án:
$A=2046$
Giải thích các bước giải:
$A=2+2^2+2^3+2^4+2^5+2^6+2^7+2^8+2^9+2^{1}0$
$→2A=2^2+2^3+2^4+2^5+2^6+2^7+2^8+2^9+2^{10}+2^{11}$
$→2A-A=2^2+2^3+2^4+2^5+2^6+2^7+2^8+2^9+2^{10}+2^{11}-(2+2^2+2^3+2^4+2^5+2^6+2^7+2^8+2^9+2^{10})$
$→A=2^{11}-2$
$→A=2048-2=2046$