\(3-\left(\frac{1}{6}-x\right)=\frac{2}{3}\)
Giúp mình nha . Cảm ơn !
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Mình làm cho bạn 2 câu khó hơn còn mấy câu còn lại dungf phương pháp quy đồng rồi chuyển vế là tính được mà
c, <=> [(x-1)/2009 ]-1 +[ (x-2)/2008] -1 = [(x-3)/2007]-1 +[(x-4)/2006]-1
<=> (x-2010)/2009 + (x-2010)/2008 = (x-2010)/2007 + (x-2010)/2006
<=> (x-2010)*(1/2009+1/2008-1/2007-1/2006)=0
=> x-2010=0 => x=2010
d, TH1 : cả hai cùng âm
=>> 2X-4 <O => X< 2
Và 9-3x<0 =>> x> 3
=>> loại
Th2 cả hai cùng dương
2x-4>O => x>2
Và 9-3x>O => x<3
=>> 2<x<3 (tm)
\(\frac{-4}{11}.\frac{2}{5}+\frac{6}{11}.\frac{-3}{10}\)
=\(\frac{2}{11}.\left(-2\right).\frac{2}{5}+\frac{2}{11}.3.\frac{-3}{10}\)
=\(\frac{2}{11}.\frac{-4}{5}+\frac{2}{11}.\frac{-9}{10}\)
=\(\frac{2}{11}.\left(\frac{-4}{5}+\frac{-9}{10}\right)\)
=\(\frac{2}{11}.\frac{-17}{10}\)
=\(\frac{-17}{55}\)
\(\left(\frac{2}{3}-1\frac{1}{2}\right):\frac{4}{3}+\frac{1}{2}\)
=\(\left(\frac{2}{3}-\frac{3}{2}\right)\times\frac{3}{4}+\frac{1}{2}\)
=\(\frac{-5}{6}\times\frac{3}{4}+\frac{1}{2}\)
=\(\frac{-5}{8}+\frac{4}{8}\)
=\(\frac{-1}{8}\)
Ai thấy đúng thì *******
\(\left(\frac{2}{3}-1\frac{1}{2}\right):\frac{4}{3}+\frac{1}{2}\)
\(=\left(\frac{2}{3}-\frac{3}{2}\right):\frac{4}{3}+\frac{1}{2}\)
\(=\left(\frac{4}{6}-\frac{9}{6}\right):\frac{4}{3}+\frac{1}{2}\)
\(=\frac{-5}{6}:\frac{4}{3}+\frac{1}{2}\)
\(=\frac{-5}{6}.\frac{3}{4}+\frac{1}{2}\)
\(=\frac{-5}{8}+\frac{1}{2}\)
\(=\frac{-5}{8}+\frac{4}{8}\)
\(=\frac{1}{8}\)
\(A=\frac{\left(1+2+3+...+100\right)\left(\frac{1}{4}+\frac{1}{6}-\frac{1}{2}\right)\left(63.1,2-21.3,6+1\right)}{1-2+3-4+....+99-100}\)
\(=\frac{\frac{100\left(100+1\right)}{2}\left(\frac{3+2-6}{12}\right)\left[63\left(1,2-1,2\right)+1\right]}{\left(1-2\right)+\left(3-4\right)+....+\left(99-100\right)}\)
\(=\frac{5050.\left(-\frac{1}{12}\right).1}{-1+\left(-1\right)+\left(-1\right)+...+\left(-1\right)}\)
\(=\frac{2525.\left(-\frac{1}{6}\right)}{-50}=\frac{101}{12}\)
\(\left(X+\frac{1}{1.3}\right)+\left(X+\frac{1}{3.5}\right)+...+\left(X+\frac{1}{23.25}\right)=11.X+\)\(\left(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}\right)\)
\(\Leftrightarrow12X+\left(\frac{1}{1.3}+\frac{1}{3.5}+...+\frac{1}{23.25}\right)+11X\)\(+\frac{\left(1+\frac{1}{3}+...+\frac{1}{81}\right)-\left(\frac{1}{3}+\frac{1}{9}+...+\frac{1}{243}\right)}{2}\)
\(\Leftrightarrow X+\frac{1}{2}\times\left(\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-...-\frac{1}{23}+\frac{1}{23}-\frac{1}{25}\right)=\frac{242}{243}:2\)
\(\Leftrightarrow X+\frac{12}{25}=\frac{121}{243}\)
\(\Leftrightarrow X=\frac{109}{6075}\)
Vậy X=109/6075
Chắc Sai kết quả chứ công thức đúng nha!!!...
Fighting!!!...
Đặt:
\(A=\frac{1}{1.3}+\frac{1}{3.5}+...+\frac{1}{23.25}\)
\(2A=\frac{2}{1.3}+\frac{2}{3.5}+...+\frac{2}{23.25}=\frac{3-1}{1.3}+\frac{5-3}{3.5}+...+\frac{25-23}{23.25}\)
\(=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{23}-\frac{1}{25}=1-\frac{1}{25}=\frac{24}{25}\)
=> \(A=\frac{12}{25}\)
Đặt \(B=\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}=\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+\frac{1}{3^4}+\frac{1}{3^5}\)
\(3B=1+\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+\frac{1}{3^4}\)
=> \(3B-B=\left(1+\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+\frac{1}{3^4}\right)-\left(\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+\frac{1}{3^4}+\frac{1}{3^5}\right)=1-\frac{1}{3^5}=\frac{242}{243}\)
=> \(2B=\frac{242}{243}\Rightarrow B=\frac{121}{243}\)
Giải phương trình:
\(\left(x+\frac{1}{1.3}\right)+\left(x+\frac{1}{3.5}\right)+...+\left(x+\frac{1}{23.25}\right)=11x+\left(\frac{1}{3}+\frac{1}{9}+...+\frac{1}{243}\right)\)
\(12x+\left(\frac{1}{1.3}+\frac{1}{3.5}+...+\frac{1}{23.25}\right)=11x+\left(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{242}\right)\)
\(12x+\frac{12}{25}=11x+\frac{121}{243}\)
\(12x-11x=\frac{121}{243}-\frac{12}{25}\)
\(x=\frac{109}{6075}\)
<=> 3 - 1/6 + x = 2/3
<=> 17/6 + x = 2/3
<=> x = 2/3 - 17/6
=> x = -13/6
Vậy x = -13/6
\(3-\left(\frac{1}{6}-x\right)=\frac{2}{3}\)
\(\Rightarrow\frac{1}{6}-x=3-\frac{2}{3}\)
\(\Rightarrow\frac{1}{6}-x=\frac{7}{3}\)
\(\Rightarrow x=\frac{1}{6}-\frac{7}{3}\)
\(\Rightarrow x=\frac{-13}{6}\)