\(\frac{a}{b}=\frac{9}{2}-\frac{1}{2}.\frac{4}{9}=\frac{77}{18}\)

\(\Rightarrow a=77,b=18\)

\(a-2b=77-2.18=41\)

ta có\(\frac{1}{2}-\frac{1}{4}-\frac{1}{8}-...-\frac{1}{1024}\)

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

tách

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

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

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

thay vào B ta có 

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

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

\(A=\frac{1}{2}-\frac{1}{4}-\cdot\cdot\cdot-\frac{1}{1024}\)

\(\Rightarrow A=\frac{1}{2}-\frac{1}{2^2}-\cdot\cdot\cdot-\frac{1}{2^{10}}\)

\(\Rightarrow2A=1-\frac{1}{2}-\cdot\cdot\cdot-\frac{1}{2^9}\)

\(\Rightarrow2A-A=\left(1-\frac{1}{2}-\cdot\cdot\cdot-\frac{1}{2^9}\right)-\left(\frac{1}{2}-\frac{1}{2^2}-\cdot\cdot\cdot-\frac{1}{2^{10}}\right)\)

\(\Rightarrow A=1-\frac{1}{2}+\frac{1}{2^{10}}\)

\(\Rightarrow A=\frac{1}{2}+\frac{1}{2^{10}}\)

\(\Rightarrow A=\frac{2^9+1}{2^{10}}\)

\(\Rightarrow A=\frac{513}{1024}\)

a)= -4/17

a)\(\frac{x-8}{2x-17}\)

Gọi d thuộc ƯC(x-8,2x-17)

=>x-8 chia hết cho d=>2(x-8) chia hết cho d=>2x-16 chia hết cho d

=>2x-17 chia hết cho d

=>(2x-16)-(2x-17) chia hết cho d

=>2x-16-2x+17 chia hết cho d

=>1 chia hết cho d

=> d thuộc Ư(1)=\([1;1]\)

=>Phân số trên tối giản vs mọi giá trị của x

Học tốt

\(\frac{1}{2}-\frac{1}{4}-\frac{1}{8}-\frac{1}{16}-.............-\frac{1}{1024}\)

=> 2S = \(2x\left(\frac{1}{2}-\frac{1}{4}-\frac{1}{8}-..........-\frac{1}{1024}\right)\)

     2S = \(1-\frac{1}{2}-\frac{1}{4}-\frac{1}{8}-..........-\frac{1}{512}\)

     2S - S = \(\left(1-\frac{1}{2}-\frac{1}{4}-\frac{1}{8}-........-\frac{1}{512}\right)\)- \(\left(\frac{1}{2}-\frac{1}{4}-\frac{1}{8}-\frac{1}{16}-........-\frac{1}{1024}\right)\)

=> S = \(1+\frac{1}{1024}=\frac{1024}{1024}+\frac{1}{1024}=\frac{1025}{1024}\)

Chắc chắn 100%

nhanh lên hộ mình vs

\(\frac{16}{45}\)

\(\frac{16}{45}\)

\(\Rightarrow x=\frac{16}{45}\)