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Bạn tự viết lại đề bài nha
\(\frac{1}{2}\)x\(\frac{2}{3}\)x\(\frac{3}{4}\)x\(\frac{4}{5}\)x...x\(\frac{18}{19}\)x\(\frac{19}{20}\)
=\(\frac{1x2x3x4x...x18x19}{2x3x4x5x...x19x20}\)
=\(\frac{1}{20}\)
= \(\frac{1}{2}\). \(\frac{2}{3}\).\(\frac{3}{4}\).\(\frac{4}{5}\). ... . \(\frac{18}{19}\).\(\frac{19}{20}\)
= \(\frac{1}{2}\)
tk cho mk nha, mik đg âm điểm huhu
<=> 3 - 1/6 + x = 2/3
<=> 17/6 + x = 2/3
<=> x = 2/3 - 17/6
=> x = -13/6
Vậy x = -13/6
\(3-\left(\frac{1}{6}-x\right)=\frac{2}{3}\)
\(\Rightarrow\frac{1}{6}-x=3-\frac{2}{3}\)
\(\Rightarrow\frac{1}{6}-x=\frac{7}{3}\)
\(\Rightarrow x=\frac{1}{6}-\frac{7}{3}\)
\(\Rightarrow x=\frac{-13}{6}\)
\(\left(\frac{2}{3}-1\frac{1}{2}\right):\frac{4}{3}+\frac{1}{2}\)
=\(\left(\frac{2}{3}-\frac{3}{2}\right)\times\frac{3}{4}+\frac{1}{2}\)
=\(\frac{-5}{6}\times\frac{3}{4}+\frac{1}{2}\)
=\(\frac{-5}{8}+\frac{4}{8}\)
=\(\frac{-1}{8}\)
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) (x-3)+(x-2)+(x-1)+....+10+11=11
(x-3)+(x-2)+(x-1)+....+10 =0
gọi số hạng của tổng vế trái là n
(x-3+10).\(\frac{n}{2}\)=0
(x+7).n:2=0
(x+7) =0
\(\Rightarrow\)x+7=0 (do n\(\ne\)0)
x=0-7
x=-7
b) \(\frac{2}{3}\left[\frac{1}{2}+\frac{3}{4}-\frac{1}{3}\right]<=x<=4\frac{1}{3}.\left[\frac{1}{2}-\frac{1}{6}\right]\)
\(\frac{2}{3}.\frac{11}{12}<=x<=\frac{13}{3}.\frac{1}{3}\)
\(\frac{11}{18}<=x<=\frac{13}{9}\)
do x\(\in\)z nên x=1
vậy x=1
\(A=\frac{\left(23\frac{11}{15}-26\frac{13}{20}\right)}{12^2+5^2}\cdot\frac{1-\frac{1}{30}-\frac{1}{42}-\frac{1}{56}}{3^2.13.2-13.5}-\frac{19}{37}\)
\(A=\frac{\left(23+\frac{11}{15}-26+\frac{13}{20}\right)}{144+25}\cdot\frac{1-\frac{1}{5.6}-\frac{1}{6.7}-\frac{1}{7.8}}{9.13.2-13.5}-\frac{19}{37}\)
\(A=\frac{\left(23+26+\frac{11}{15}-\frac{13}{20}\right)}{169}\cdot\frac{1-\left(\frac{1}{5}-\frac{1}{6}\right)-\left(\frac{1}{6}-\frac{1}{7}\right)-\left(\frac{1}{7}-\frac{1}{8}\right)}{13.\left(9.2-5\right)}-\frac{19}{37}\)
\(A=\frac{49+\frac{44}{60}-\frac{39}{60}}{169}\cdot\frac{1-\frac{1}{5}+\frac{1}{6}-\frac{1}{6}+\frac{1}{7}-\frac{1}{7}+\frac{1}{8}}{13.13}-\frac{19}{37}\)
\(A=\frac{49+\frac{1}{20}}{169}\cdot\frac{1-\frac{1}{5}+\frac{1}{8}}{169}-\frac{19}{37}\)
\(A=\frac{49\frac{1}{20}}{169}\cdot\frac{\frac{4}{5}+\frac{5}{40}}{169}-\frac{19}{37}\)
\(A=\frac{981}{169}\cdot\frac{\frac{32}{40}+\frac{5}{40}}{169}-\frac{19}{37}\)
\(A=\frac{981}{169}\cdot\frac{\frac{37}{40}}{169}-\frac{19}{37}\)
\(A=\frac{981.\frac{37}{40}}{169^2}-\frac{19}{37}\)
\(A=\frac{\frac{36297}{40}}{28561}-\frac{19}{37}\)
\(A=\frac{907,425}{28561}-\frac{19}{37}\)
\(A=\frac{33574,725}{1056757}-\frac{542659}{1056757}\)
\(A=\frac{-509084,275}{1056757}=-0,04604282...\)
Mik chỉ làm đc thế này thôi, ôn thi học kì II tốt nha bạn!
\(\frac{-5}{3}-\left(\frac{4}{5}-\frac{1}{2}\right)-\left|\frac{3}{4}-\frac{5}{2}+\frac{1}{3}\right|\)
\(=\frac{-5}{3}-\frac{4}{5}+\frac{1}{2}-\left|\frac{3}{4}+\frac{-5}{2}+\frac{1}{3}\right|\)
\(=\frac{-5}{3}-\frac{4}{5}+\frac{1}{2}-\left(\frac{3}{4}+\frac{-5}{2}+\frac{1}{3}\right)\)
\(=\frac{-5}{3}-\frac{4}{5}+\frac{1}{2}-\frac{3}{4}+\frac{5}{2}-\frac{1}{3}\)
\(=\left(\frac{-5}{3}-\frac{1}{3}\right)+\left(\frac{1}{2}+\frac{5}{2}\right)-\left(\frac{4}{5}+\frac{3}{4}\right)\)
\(=\frac{-6}{3}+\frac{6}{2}-\left(\frac{16}{20}+\frac{15}{20}\right)\)
\(=-2+3-\frac{31}{20}\)
\(=1-\frac{31}{20}=\frac{-11}{20}\)
\(\frac{-5}{3}-\left(\frac{4}{5}-\frac{1}{2}\right)-\left|\frac{3}{4}-\frac{5}{2}+\frac{1}{3}\right|\)
\(=\frac{-5}{3}-\frac{4}{5}+\frac{1}{2}-\left|\frac{3}{4}+\frac{-5}{2}+\frac{1}{3}\right|\)
\(=\frac{-5}{3}-\frac{4}{5}+\frac{1}{2}-\left(\frac{3}{4}+\frac{-5}{2}+\frac{1}{3}\right)\)
\(=\frac{-5}{3}-\frac{4}{5}+\frac{1}{2}-\frac{3}{4}+\frac{5}{2}-\frac{1}{3}\)
\(=\left(\frac{-5}{3}-\frac{1}{3}\right)+\left(\frac{1}{2}+\frac{5}{2}\right)-\left(\frac{4}{5}+\frac{3}{4}\right)\)
\(=\frac{-6}{3}+\frac{6}{2}-\left(\frac{16}{20}+\frac{15}{20}\right)\)
\(=\frac{-6}{3}+\frac{6}{2}-\left(\frac{16}{20}+\frac{15}{20}\right)\)
\(=1-\frac{31}{20}=\frac{-11}{20}\)
Ta có : \(5\cdot\left(\frac{1}{5}+\frac{1}{17}\right)-\left(\frac{2}{5}+\frac{2}{17}+\frac{9}{15}+\frac{12}{68}\right)\)
\(=\) \(5\cdot\frac{1}{5}+5\cdot\frac{1}{17}-\left(\frac{2}{5}+\frac{2}{17}+\frac{3}{5}+\frac{3}{17}\right)\)
\(=\) \(1+\frac{5}{17}-\left[\left(\frac{2}{5}+\frac{3}{5}\right)+\left(\frac{2}{17}+\frac{3}{17}\right)\right]\)
\(=\) \(1+\frac{5}{17}-\left(1+\frac{5}{17}\right)\)
\(=\) \(1+\frac{5}{17}-1-\frac{5}{17}\)
\(=\)\(0\)
Vậy ...
Tk ủng hộ mk nha các bn ❣❣ C.ơn nhiều ^^
\(\frac{1}{7}-\frac{8}{7}:8-3:\frac{3}{4}.\left(-2\right)^2\)
=\(\frac{1}{7}-\frac{1}{7}-4.4\)
=0-16
=-16
\(\left[x-\frac{1}{3}\right]=\frac{1}{2}\)
=>\(x-\frac{1}{3}=-\frac{1}{2}\)
\(x=-\frac{1}{2}+\frac{1}{3}\)
\(x=-\frac{1}{6}\)
ai k mk mk k laij