Toan lop 5 ha ma

rút gọn

a) |x| = 1212

=> x = 1212 hoặc -1212

T_T các câu kia tườn tự vậy thôi bạn, dài quá @_@

học tốt -_-"

a) \(\left|x\right|=1212\)

\(\Rightarrow\orbr{\begin{cases}x=1212\\x=-1212\end{cases}}\)

b) \(\left|2x+1212\right|=3434\)

\(\Rightarrow\orbr{\begin{cases}2x+1212=3434\\2x+1212=-3434\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}2x=2222\\2x=-4646\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=1111\\x=-2323\end{cases}}\)

\(\frac{1010+1111+1212+1313+1414+1515+1616+1717}{2020+2121+2222+2323+2424+2525+2626+2727}\)

\(=\frac{101.10+101.11+...+101.17}{101.20+101.21+...+101.27}\)

\(=\frac{101.\left(10+11+...+17\right)}{101.\left(20+21+...+27\right)}\)

\(=\frac{108}{188}\)

\(=\frac{27}{47}\)

\(2>\left(\frac{1}{6}+\frac{2}{15}+\frac{3}{40}+\frac{4}{96}\right)\cdot5.y>\frac{5}{6}\)

\(\Rightarrow2>\left(\frac{1}{6}+\frac{2}{15}+\frac{3}{40}+\frac{1}{24}\right):5.y>\frac{5}{6}\)

\(\Rightarrow2>\left(\frac{20}{120}+\frac{16}{120}+\frac{9}{120}+\frac{5}{120}\right):5.y>\frac{5}{6}\)

\(\Rightarrow2>\frac{5}{12}:5.y>\frac{5}{6}\)

\(\Rightarrow2>\frac{1}{12}.y>\frac{5}{6}\)

Đặt :\(\frac{1}{12}.y=2\Rightarrow y=2:\frac{1}{12}=24\)

\(\frac{1}{12}.y=\frac{5}{6}\Rightarrow y=\frac{5}{6}:\frac{1}{12}=10\)

\(\Rightarrow24>y>10\)

\(\Rightarrow y\in\left\{11;12;...;23\right\}\)

ko biết

I am sorry

Kb nhé

=0 vì đó là các cặp số đối

chính xác 100% 

     \(\frac{1313}{1212}:x=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\)\(\frac{1}{5.6}\)

\(\Leftrightarrow\frac{13}{12}:x=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)

\(\Leftrightarrow\frac{13}{12}:x=1-\frac{1}{6}\)

\(\Leftrightarrow\frac{13}{12}:x=\frac{5}{6}\)

\(\Leftrightarrow x=\frac{13}{12}:\frac{5}{6}\)

\(\Leftrightarrow x=\frac{13}{10}\)

  Vậy \(x=\frac{13}{10}\)

                            ~~~~~Hok tốt ~~~~~

a,\(\frac{1313}{1212}\div x=\frac{1}{1\times2}+\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}\)

\(\frac{13}{12}\div x=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)

\(\frac{13}{12}\div x=1-\frac{1}{6}\)

\(\frac{13}{12}\div x=\frac{5}{6}\)

\(x=\frac{13}{12}\div\frac{5}{6}\)

\(x=\frac{13}{12}\times\frac{6}{5}\)

\(x=\frac{13}{10}\)

Chúc bạn hok tốt !

\(\frac{1313}{1212}:x=\frac{1}{1x2}+\frac{1}{2x3}+...+\frac{1}{5x6}\)

\(\frac{1313}{1212}:\frac{101}{101}=\frac{13}{12}:x=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{5}-\frac{1}{6}\)

\(\frac{13}{12}:x=1-\frac{1}{6}\)

\(\frac{13}{12}:x=\frac{5}{6}\)

\(x=\frac{13}{12}:\frac{5}{6}\)

\(x=\frac{78}{60}=\frac{13}{10}\)

       \(\frac{1313}{1212}:x=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\)\(\frac{1}{5.6}\)

\(\Leftrightarrow\frac{13}{12}:x=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)

\(\Leftrightarrow\frac{13}{12}:x=1-\frac{1}{6}\)

\(\Leftrightarrow\frac{13}{12}:x=\frac{5}{6}\)

\(\Leftrightarrow x=\frac{13}{12}:\frac{5}{6}\)

\(\Leftrightarrow x=\frac{13}{10}\)

                  Hok tốt

\(1,\frac{1212}{1515}+\frac{1212}{3535}+\frac{1212}{6363}+\frac{1212}{9999}=\frac{12}{15}+\frac{12}{35}+\frac{12}{63}+\frac{12}{99}=6\left(\frac{2}{15}+\frac{2}{35}+\frac{2}{63}+\frac{2}{99}\right)=6\left(\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+\frac{2}{9.11}\right).Tacocongthuc:\frac{1}{n}-\frac{1}{n+k}=\frac{k}{n\left(n+k\right)}\Rightarrow\frac{1212}{1515}+\frac{1212}{3535}+\frac{1212}{6363}+\frac{1212}{9999}=6\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-.....-\frac{1}{11}\right)=6\left(\frac{1}{3}-\frac{1}{11}\right)=\frac{48}{33}=\frac{16}{11}\)

\(2,\left(x+1\right)+\left(x+2\right)+.....+\left(x+211\right)=211x+\left(1+2+....+211\right)=211x+\frac{212.211}{2}=211x+22366=23632\Leftrightarrow211x=23632-22366=1266\Leftrightarrow x=6\)

a, \(14:\left(4\frac{2}{3}:1\frac{5}{9}\right)+14:\left(\frac{2}{3}+\frac{8}{9}\right)\)

=> \(14:\frac{28}{9}+14:\frac{14}{9}=>14.\frac{9}{28}+14.\frac{9}{14}\)

=> 14. ( \(\frac{9}{28}+\frac{9}{14}\) )

=> \(14.\frac{27}{28}=\frac{419}{28}\)

b, \(\frac{1212}{1515}+\frac{1212}{3535}+\frac{1212}{6363}+\frac{1212}{9999}\)

=> \(\frac{4}{5}+\frac{12}{35}+\frac{4}{21}+\frac{4}{33}\)

=> \(\frac{8}{7}+\frac{24}{77}=\frac{16}{11}\)

bài 2 :

( x + 1 ) + ( x + 2 ) + ... + ( x + 211 ) = 23632

=> ( x + x + x + ... + x ) + ( 1 + 2 + 3 + ... + 211 ) = 23632

=> 211x + 22366 = 23632

=> 211x = 23632 - 22366

=> 211x = 1266

=> x = 1266 : 211

x = 6