Sao vậy bạn

what ? 

Đặt \(A=-1-\frac{1}{2}-\frac{1}{4}-\frac{1}{8}-...-\frac{1}{1024}\)

\(A=-\left(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{1024}\right)\)

Giả sử A = -B

\(B=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{1024}\)

\(2B=2+1+\frac{1}{2}+\frac{1}{4}+...+\frac{1}{512}\)

\(2B-B=2-\frac{1}{1024}\)

\(B=\frac{2047}{1024}\)

=> \(A=-\frac{2047}{1024}\)

X + 124 = 224

          X = 224 - 124

          X = 100.k mình k lại

THANKS

mk cung dang mac bai nay nen mong nhieu bn giup do chi nha !