B= \(\frac{1}{2^1}+\frac{1}{2^2}+\frac{1}{2^3}+.....+\frac{1}{2^9}+\frac{1}{2^{10}}.\)
\(2B=\frac{1}{2^2}+\frac{1}{2^3}+......+\frac{1}{2^{11}}.\)
\(B=\)\(\frac{1}{2^2}+\frac{1}{2^3}+......+\frac{1}{2^{11}}.\)-\(-\frac{1}{2^1}+\frac{1}{2^2}+\frac{1}{2^3}+.....+\frac{1}{2^9}+\frac{1}{2^{10}}.\)
ĐẾN ĐAY BN TỰ LÀM ĐƯỢC RỒI