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Mình nghĩ đề thế này mới tính hợp lí được
2 ) B = \(1\frac{6}{41}.\left(\frac{12+\frac{12}{19}-\frac{12}{37}-\frac{12}{53}}{3+\frac{3}{19}-\frac{3}{37}-\frac{3}{53}}:\frac{4+\frac{4}{17}+\frac{4}{19}+\frac{4}{2006}}{5+\frac{5}{17}+\frac{5}{19}+\frac{5}{2006}}\right).\frac{124242423}{237373735}\)
B = 47/41 . ( 12/3 : 4/5 ) . 123/235
B = 47/41 . ( 4 : 4/5 ) . 123/235
B = 47/41 . 5 . 123/235
B = \(\frac{47.5.123}{41.235}\)
B = 3
1 ) A = \(\frac{636363.37-373737.63}{1+2+3+...+2006}\)
A = \(\frac{63.10101.37-37.10101.63}{1+2+3+...+2006}\)
A = \(\frac{0}{1+2+3+...+2006}\)
A = 0
Tớ biết làm đúng 100%:
\((x\cdot1+x\cdot\frac{7}{9})\left(x\cdot1+x\cdot\frac{7}{20}\right)...\left(x\cdot1+x\cdot\frac{7}{9200}\right)=\frac{186}{25}\)
\(x\cdot\left(1+\frac{7}{9}\right)\cdot x\left(1+\frac{7}{20}\right)\cdot...\cdot x\left(1+\frac{7}{9200}\right)=\frac{186}{25}\)
\(\left(x\cdot x\cdot...\cdot x\right)(\frac{16}{9}+\frac{27}{20}+...+\frac{9207}{9200})=\frac{186}{25}\)
\(\left(x\cdot x\cdot...\cdot x\right)\left(\frac{2\cdot8}{1\cdot9}+\frac{3\cdot9}{2\cdot10}+...+\frac{93\cdot99}{92\cdot100}\right)=\frac{186}{25}\)
\(x^{92}\cdot\frac{2\cdot8\cdot3\cdot9\cdot...\cdot93\cdot99}{1\cdot9\cdot2\cdot10\cdot...\cdot92\cdot100}=\frac{186}{25}\)
\(x^{92}\cdot\frac{\left(2\cdot3\cdot...\cdot93\right)\cdot\left(8\cdot9\cdot...\cdot99\right)}{\left(1\cdot2\cdot...\cdot92\right)\cdot\left(9\cdot10\cdot...\cdot100\right)}=\frac{186}{25}\)
\(x^{92}\cdot\frac{93\cdot8}{100}=\frac{186}{25}\)
\(x^{92}\cdot\frac{186}{25}=\frac{186}{25}\)
\(x^{92}=\frac{186}{25}:\frac{186}{25}\)
\(x^{92}=1\Rightarrow x=1\)
cô tớ giải rồi . x=1 (đúng 100%)
\(\frac{-7}{11}.\frac{11}{19}+\frac{-7}{11}.\frac{8}{19}+\frac{-4}{11}\)
\(=\frac{-7}{11}.\left(\frac{11}{19}+\frac{8}{19}\right)+\frac{-4}{11}\)
\(=\frac{-7}{11}.1+\frac{-4}{11}\)
\(=\frac{-7}{11}+\frac{-4}{11}=\frac{-11}{11}=-1\)
~ Hok tốt ~
Đặt \(B=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2018.2019}\)
\(\Rightarrow B=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2018}-\frac{1}{2019}\)
\(\Rightarrow B=1-\frac{1}{2019}\)
\(\Rightarrow B=\frac{2018}{2019}\)
\(1\frac{13}{15}.0,75-\left(\frac{8}{15}+25\%\right).\frac{24}{47}-3\frac{12}{13}:3\)
\(=\frac{28}{15}.\frac{3}{4}-\left(\frac{8}{15}+\frac{1}{4}\right).\frac{24}{47}-\frac{51}{13}:3\)
\(=\frac{7}{5}-\frac{47}{60}.\frac{24}{47}-\frac{17}{13}\)
\(=\frac{7}{5}-\frac{2}{5}-\frac{17}{13}\)
\(=\frac{-4}{13}\)
\(4\frac{1}{3}.\left(\frac{1}{6}-\frac{1}{2}\right)\le x\le\frac{2}{3}.\left(\frac{1}{3}-\frac{1}{2}-\frac{3}{4}\right)\)
\(\Leftrightarrow\frac{13}{3}.\frac{-1}{3}\le x\le\frac{2}{3}.\frac{-11}{12}\)
\(\Leftrightarrow\frac{-13}{9}\le x\le\frac{-11}{18}\)
\(\Leftrightarrow x=-1\)
k chép đề
3/2.A=\(\frac{3}{4}+\left(\frac{3}{2}\right)^2+\left(\frac{3}{2}\right)^3+\left(\frac{3}{2}\right)^4+\left(\frac{3}{2}\right)^5+...+\left(\frac{3}{2}\right)^{2013}\)
3/2A-A=(\(\frac{3}{4}+\left(\frac{3}{2}\right)^2+\left(\frac{3}{2}\right)^3+\left(\frac{3}{2}\right)^4+\left(\frac{3}{2}\right)^5+...+\left(\frac{3}{2}\right)^{2013}\)) - (\(\frac{1}{2}+\frac{3}{2}+\left(\frac{3}{2}\right)^2+\left(\frac{3}{2}\right)^3+\left(\frac{3}{2}\right)^4+...+\left(\frac{3}{2}\right)^{2012}\))
1/2 . A =\(\frac{1}{2}+\left(\frac{3}{2}\right)^{2013}\)
A=\(\frac{\frac{1}{2}+\left(\frac{3}{2}\right)^{2013}}{2}\)
B-A=\(\frac{\left(\frac{3}{2}\right)^{2018}}{2}-\)\(\frac{\frac{1}{2}+\left(\frac{3}{2}\right)^{2013}}{2}\)
\(B-A=\frac{\frac{1}{2}}{2}=\frac{1}{2}:2=\frac{1}{4}\)
\(a,\frac{2}{3}\cdot x-\frac{4}{7}=\frac{1}{8}\)
\(\Leftrightarrow\frac{2}{3}\cdot x=\frac{1}{8}+\frac{4}{7}\)
\(\Leftrightarrow\frac{2}{3}\cdot x=\frac{7}{56}+\frac{32}{56}\)
\(\Leftrightarrow\frac{2}{3}\cdot x=\frac{39}{56}\)
\(\Leftrightarrow x=\frac{39}{56}:\frac{2}{3}=\frac{39}{56}\cdot\frac{3}{2}=\frac{39\cdot3}{56\cdot2}=\frac{117}{112}\)
\(b,\frac{2}{7}-\frac{8}{9}\cdot x=\frac{2}{3}\)
\(\Leftrightarrow\frac{8}{9}\cdot x=\frac{2}{7}-\frac{2}{3}\)
\(\Leftrightarrow\frac{8}{9}\cdot x=\frac{6}{21}-\frac{14}{21}\)
\(\Leftrightarrow\frac{8}{9}\cdot x=\frac{-8}{21}\)
\(\Leftrightarrow x=\frac{-8}{21}:\frac{8}{9}=\frac{-8}{21}\cdot\frac{9}{8}=\frac{-8\cdot9}{21\cdot8}=\frac{-1\cdot3}{7\cdot1}=\frac{-3}{7}\)
Làm nốt hai bài cuối đi nhé
Study well >_<
Mk k chép lại đề bài nha
a)\(\frac{2}{3}.x=\frac{1}{8}+\frac{4}{7}\)
\(\frac{2}{3}.x=\frac{7}{56}+\frac{32}{56}\)
\(\frac{2}{3}.x=\frac{39}{56}\)
\(x=\frac{39}{56}:\frac{2}{3}\)
\(x=\frac{39}{56}.\frac{3}{2}\)
\(x=\frac{117}{112}\)
Mk sợ sai lém!!!
\(\frac{2}{3}+\frac{1}{3}=\frac{6+3}{3}=\frac{9}{3}=3\)
\(\frac{3}{4}+\frac{2}{4}+\frac{1}{4}=\left(\frac{3}{4}+\frac{1}{4}\right)+\frac{1}{2}=1+\frac{1}{2}=1\frac{1}{2}=\frac{3}{2}\)
\(\frac{4}{5}+\frac{3}{5}+\frac{2}{5}+\frac{1}{5}=\left(\frac{4}{5}+\frac{1}{5}\right)+\left(\frac{3}{5}+\frac{2}{5}\right)=2+2=4\)
\(\frac{5}{6}+\frac{4}{6}+\frac{3}{6}+\frac{2}{6}+\frac{1}{6}=\left(\frac{5}{6}+\frac{1}{6}\right)+\left(\frac{4}{6}+\frac{2}{6}\right)+\frac{1}{2}=1+1\)\(+\frac{1}{2}=2\frac{1}{2}=\frac{5}{2}\)
ngu LÊ MĨ LINH
theo thứ tự :1,6/4 =1 và 1/2,2,5/2,500
\(\frac{\frac{2}{33}+\frac{2}{25}+\frac{2}{19}}{\frac{3}{33}+\frac{3}{25}+\frac{3}{19}}=\frac{2\left(\frac{1}{33}+\frac{1}{25}+\frac{1}{19}\right)}{3\left(\frac{1}{33}+\frac{1}{25}+\frac{1}{19}\right)}=\frac{2}{3}\)
= \(\frac{2\left(\frac{1}{33}+\frac{1}{25}+\frac{1}{19}\right)}{3\left(\frac{1}{33}+\frac{1}{25}+\frac{1}{19}\right)}=\frac{2}{3}\)