2A=2^2+2^3+......+2^2009+2^2010
2A-A=(2^2+2^3+......+2^2009+2^2010)-(2+2^2+2^3+...+2^2009)
A=2+2^2010
Trả lời:
A = 2 + 23 + 25 + 27 + 29 + ... +22009
=> 22A = 22 ( 2 + 23 + 25 + 27 + 29 + ... +22009 )
=> 4A = 23 + 25 + 27 + 29 + 211 + ... + 22011
=> 4A - A = ( 23 + 25 + 27 + 29 + 211 + ... + 22011 ) - ( 2 + 23 + 25 + 27 + 29 + ... + 22009 )
=> 3A = 23 + 25 + 27 + 29 + 211 + ... + 22011 - 2 - 23 - 25 - 27 - 29 - ... - 22009
=> 3A = 22011 - 2
=> A = \(\frac{2^{2011}-2}{3}\)