Question

1+2的-1次方+2的-2次方+2的-3次方+.+2的-2007次方,等于多少!

Answer 1

1+2^-1+2^-2+.+2^-2007

=(1-(1/2)^2008)/(1-1/2)

=2(1-1/2^2008)

=(2^2009-1)/2^2008