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Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời. A) 9 - 13/4 + 4/3 : 2 =9 - 13/4 + 2/3 =9 - 47/12 =61/12 B) 13/14 : X + 4/5 = 9 13/4 :X = 9 - 4/5 13/4 : X = 41/5 X=13/4 : 41/5 X=65/164 Bai 1. a) 9 - 13/4 +4/3 : 2 = 9 - 13/4 +4/3 x 1/2 = 9 - 13/4 + 2/3 = 36/4 - 13/4 + 2/3 = 23/4 + 2/3 = 69/12 + 8/12 = 77/12 Bai 2. Tim x 13/4 : x + 4/5 = 9 13/4 : x = 9 - 4/5 13/4 : x = 45/5 - 4/5 13/4 : x = 41/5 x = 13/4 : 41/5 x = 13/4 x 5/41 x = 65/164 Vay x = 65/164 có ai giúc mk ko mk đăng nhiều lần rồi răng ko ai chịu giúc nhỉ \(\frac{2x-4,36}{0,125}=0,25.42,9-11,7.0,25+0,25.0,8\) \(\Leftrightarrow\frac{2x-4,36}{0,125}=0,25.\left(42,9-11.7+0,8\right)\) \(\Leftrightarrow\frac{2x-4,36}{0,125}=0,25.32\) \(\Leftrightarrow\frac{2x-4,36}{0,125}=8\) \(\Leftrightarrow2x-4,36=1\) \(\Leftrightarrow2x=5,36\) \(\Leftrightarrow x=2,68\) b) \(N=\frac{1}{1.5}+\frac{1}{5.10}+\frac{1}{10.15}+\frac{1}{15.20}+...+\frac{1}{2005.2010}\) \(\Leftrightarrow N=\frac{1}{5}\left(1-\frac{1}{5}+\frac{1}{5}-\frac{1}{10}+\frac{1}{10}-\frac{1}{15}+\frac{1}{15}-\frac{1}{20}+...+\frac{1}{2005}-\frac{1}{2010}\right)\) \(\Leftrightarrow N=\frac{1}{5}\left(1-\frac{1}{2010}\right)\) \(\Leftrightarrow N=\frac{1}{5}.\frac{2009}{2010}=\frac{2009}{10050}\) Bài 1: a)\(\frac{2\cdot x-4,36}{0,125}=0,25\cdot42,9-11,7\cdot0,25+0,25\cdot0,8\) \(\frac{2\cdot x-4,36}{0,125}=0,25\cdot\left(42,9-11,7+0,8\right)\) \(\frac{2\cdot x-4,36}{0,125}=0,25\cdot32\) \(\frac{2\cdot x-4,36}{0,125}=8\) \(2\cdot x-4,36=8\cdot0,125\) \(2\cdot x-4,36=1\) \(2\cdot x=1+4,36\) \(2\cdot x=5,36\) \(x=\frac{5,36}{2}=2,68\) b) \(N=\frac{1}{1\cdot5}+\frac{1}{5\cdot10}+\frac{1}{10\cdot15}+\frac{1}{15\cdot20}+...+\frac{1}{2005\cdot2010}\) \(4N=\frac{4}{1\cdot5}+\frac{4}{5\cdot10}+\frac{4}{10\cdot15}+\frac{4}{15\cdot20}+...+\frac{4}{2005\cdot2010}\) \(4N=1-\frac{1}{5}+\frac{1}{5}-\frac{1}{10}+\frac{1}{10}-\frac{1}{15}+\frac{1}{15}-\frac{1}{20}+...+\frac{1}{2005}-\frac{1}{2010}\) \(4N=1-\frac{1}{2010}=\frac{2009}{2010}\) \(N=\frac{2009}{2010}\div4=\frac{2009}{8040}\) Bài 2: a) ( x + 5,2 ) : 3,2 = 4,7 ( dư 0,5 ) \(x+5,2=4,7\cdot3,2+0,5\) \(x+5,2=15,54\) \(x=15,54-5,2=10,34\) b)\(A=\frac{4047991-2010\cdot2009}{4050000-2011\cdot2009}\) \(A=\frac{4047991-2010\cdot2009}{4050000-2009-2010\cdot2009}\) \(A=\frac{4047991-2010\cdot2009}{4047991-2010\cdot2009}=1\) Bài 3: a) \(104,5\cdot x-14,1\cdot x+9,6\cdot x=25\) \(x\cdot\left(104,5-14,1+9,6\right)=25\) \(x\cdot100=25\) \(x=\frac{25}{100}=\frac{1}{4}=0,25\) b) \(T=\frac{2009\cdot2010+2000}{2011\cdot2010-2020}\) \(T=\frac{2009\cdot2010+2000}{2009\cdot2010+4020-2020}\) \(T=\frac{2009\cdot2010+2000}{2009\cdot2010+2000}=1\) \(\frac{2}{5}×\frac{3}{4}+\frac{6}{15}:\frac{4}{9}×5\) \(=\frac{3}{10}+\frac{6}{15}×\frac{9}{4}×5\) \(=\frac{3}{10}+\frac{9}{10}×5\) \(=\frac{3}{10}+\frac{9}{2}\) \(=\frac{3}{10}+\frac{45}{10}\) \(=\frac{3+45}{10}\) \(=\frac{48}{10}=\frac{24}{5}=4,8\) \(\frac{3}{10}+\frac{9}{10}\cdot5=\frac{3}{10}+\frac{45}{10}=\frac{48}{10}=\frac{24}{5}\) khong can ghi de bai nha \(\frac{1}{5.8}\)\(+\frac{1}{8.11}+\frac{1}{11.14}+...+\frac{1}{x\left(x+3\right)}=\frac{98}{1545}\) \(\Leftrightarrow\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}+...+\frac{3}{x\left(x+3\right)}=3.\frac{98}{1545}\) \(\Leftrightarrow\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}+...+\frac{3}{x\left(x+3\right)}=\frac{98}{515}\) \(\Leftrightarrow\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+...+\frac{1}{x}-\frac{1}{x+3}=\frac{98}{515}\) \(\Leftrightarrow\frac{1}{5}-\frac{1}{x+3}=\frac{98}{515}\) \(\Leftrightarrow\frac{1}{x+3}=\frac{1}{5}-\frac{98}{515}\) \(\Leftrightarrow\frac{1}{x+3}=\frac{1}{103}\) \(\Leftrightarrow x+3=103\) \(\Leftrightarrow x\)\(=103-3\) \(\Leftrightarrow x\)\(=100\) Vậy x = 100 ~~~~~~~Hok tốt~~~~~~~~ ta có \(\frac{1}{5.8}+\frac{1}{8.11}+...\frac{1}{x.\left(x+3\right)}\)\(=\frac{1}{3}\left(\frac{3}{5.8}+\frac{3}{8.11}+...+\frac{3}{x.\left(x+3\right)}\right)\)\(=\frac{1}{3}.\left(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{x}-\frac{1}{x+3}\right)\) \(\Rightarrow\frac{1}{3}.\left(\frac{1}{5}-\frac{1}{x+3}\right)=\frac{98}{1545}\) \(\Rightarrow\frac{1}{5}-\frac{1}{x+3}=\frac{98}{1545}:\frac{1}{3}=\frac{98}{515}\) \(\Rightarrow\frac{1}{x+3}=\frac{1}{5}-\frac{98}{515}=\frac{1}{103}\) \(\Rightarrow x+3=103\) \(\Rightarrow x=100\) nhớ k nha \(\left(1+x\right)+\left(2+x\right)+\left(3+x\right)+\)\(\left(4+x\right)+\left(5+x\right)=10\times5\) \(\left(1+2+3+4+5\right)+\left(x+x+x+x+x\right)=50\) \(15+5x=50\) \(5x=35\) \(x=7\) Vậy \(x=7\) \(\left(1+x\right)+\left(2+x\right)+\left(3+x\right)+\left(4+x\right)+\left(5+x\right)=10\times5\) \(\Rightarrow1+x+2+x+3+x+4+x+5+x=50\) \(\Rightarrow\left(1+2+3+4+5\right)+\left(x+x+x+x+x\right)=50\) \(\Rightarrow15+5x=50\) \(\Rightarrow5x=50-15\) \(\Rightarrow5x=35\) \(\Rightarrow x=35:5\) \(\Rightarrow x=7\). a, 5 x ( 4 + 6 x X ) = 290 4 + 6 x X = 290 : 5 4 + 6 x X = 58 6 x X = 58 - 4 6 x X = 54 X = 54 : 6 X = 9 b, ( 15 x 24 - X ) : 0,25 = 100 : \(\frac{1}{4}\) ( 15 x 24 - X ) : 0,25 = 400 15 x 24 - X = 400 x 0,25 15 x 24 - X = 100 360 - X = 100 X = 360 - 100 X = 260 c) X x 4,8 + 5,2 x X = 160 X x ( 4,8 + 5,2 ) = 160 X x 10 = 160 X = 160 : 10 X = 16 d) \(\frac{17}{5}:x=\frac{34}{5}:\frac{4}{3}\) \(\frac{17}{5}:x=\frac{51}{10}\) \(x=\frac{17}{5}:\frac{51}{10}\) \(x=\frac{2}{3}\) Chính xác đến 100 % Học tốt #
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Khách
CM
Cao Minh Tâm
30 tháng 10 2017
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