\(\frac{9999}{10000}\)+ \(\frac{9999}{10000}\)=
Tính nhanh : \(\frac{10000}{10001}-\frac{9999}{10000}+\frac{1}{9999}-\frac{1}{10000}+...+\frac{3}{4}-\frac{2}{3}+\frac{1}{2}-\frac{1}{3}\)
\(\frac{9999}{10000}\)+ \(\frac{10000}{9999}\)= ?
\(\frac{9999}{10000}+\frac{9999}{10000}=1\)
Học tốt
Câu hỏi :
\(\frac{9999}{10000}+\frac{10000}{9999}\)
Trả lời :
\(\frac{9999}{10000}+\frac{10000}{9999}=2,00000001\)
hok tốt~~
Cho A = \(\frac{1}{2}.\frac{3}{4}.\frac{5}{6}...\frac{9998}{9999}.\frac{10000}{10000}\)
So sánh A và 0,01
Đặt A = \(\frac{2}{3}.\frac{4}{5}.\frac{6}{7}...\frac{9998}{9999}.\frac{10000}{10000}\)
Rõ ràng A < A'
=> A2 < A . A' \(=\frac{1}{10000}=\frac{1}{100^2}\)
Nên A < 0,01
A = \(\frac{3}{4}.\frac{8}{9}.\frac{5}{6}.....\frac{9999}{10000}\)
Tính x=\(\frac{3}{4}+\frac{8}{9}+\frac{15}{16}+...+\frac{9999}{10000}\)
\(x=\frac{3}{4}+\frac{8}{9}+\frac{15}{16}+...+\frac{9999}{10000}\)
\(x=\frac{1.3}{2.2}+\frac{2.4}{3.3}+\frac{3.5}{4.4}+...+\frac{99.101}{100.100}\)
\(x=\frac{1.2...99}{2.3...100}.\frac{3.4...101}{2.3...100}\)
\(x=\frac{1}{100}.\frac{101}{2}\)
\(x=\frac{101}{200}\)
\(X=\frac{1.3}{2.2}+\frac{2.4}{3.3}+\frac{3.5}{4.4}+...+\frac{99.101}{100.100}\)
\(X=\frac{1.2.3....99}{2.3.4....100}.\frac{3.4.5....101}{2.3.4....100}\)
\(X=\frac{1}{100}.\frac{101}{2}\)
\(X=\frac{101}{200}\)
Study well
\(\frac{1}{2}.\frac{3}{4}.....\frac{9999}{10000}\)so sánh A và 0,01
\(A=\frac{3}{4}.\frac{8}{9}.\frac{15}{16}.....\frac{9999}{10000}=\frac{3.8.15....9999}{4.9.16....10000}=?\)
Tính \(M=\frac{3}{4}.\frac{8}{9}.\frac{15}{16}...\frac{9999}{10000}\)
\(M=\frac{3}{4}.\frac{8}{9}.....\frac{9999}{10000}=\frac{1\cdot3}{2\cdot2}\cdot\frac{2\cdot4}{3\cdot3}\cdot....\cdot\frac{99\cdot101}{100\cdot100}=\frac{1\cdot3\cdot2\cdot4\cdot...\cdot99\cdot101}{2^2\cdot3^2\cdot...\cdot100^2}=\frac{1\cdot101}{2\cdot100}=\frac{101}{200}\)Vậy M = \(\frac{101}{200}\)
\(M=\frac{3}{4}.\frac{8}{9}.\frac{15}{16}....\frac{9999}{10000}\)
\(M=\frac{1.3}{2^2}.\frac{2.4}{3^2}.\frac{3.5}{4^2}....\frac{99.101}{100^2}=\frac{1.2.3...99}{2.3.4...100}.\frac{3.4.5...101}{2.3.4...100}=\frac{1}{100}.\frac{101}{2}=\frac{101}{200}\)
\(\frac{3}{4}x\frac{8}{9}x\frac{15}{16}x.......x\frac{9999}{10000}\)
\(\frac{3}{4}x\frac{8}{9}x\frac{15}{16}x...x\frac{9999}{10000}\)
\(=\frac{1.3}{2^2}.\frac{2.4}{3^2}.\frac{3.5}{4^2}.....\frac{99.101}{100^2}\)
\(=\frac{1.3.2.4.3.5.....99.101}{2.2.3.3.4.4.....100.100}\)
\(=\frac{1.2.3.....99}{2.3.4.....100}.\frac{3.4.5.....101}{2.3.4.....100}\)
\(=\frac{1}{100}.\frac{101}{2}=\frac{101}{200}\)
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