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a) \(\frac{2}{7}+\frac{5}{7}.\frac{14}{35}=\frac{2}{7}+\frac{2}{7}=\frac{4}{7}\)
b) \(\left(\frac{31}{20}-\frac{36}{45}\right).\frac{36}{499}=\frac{3}{4}.\frac{36}{499}=\frac{27}{499}\)
c) \(4\frac{3}{8}+0,37+\frac{1}{8}+1,28+\frac{2}{5}+3\frac{1}{12}\)
\(=\frac{35}{8}+\frac{37}{100}+\frac{1}{8}+\frac{32}{25}+\frac{2}{5}+\frac{37}{12}\)
\(=\left(\frac{35}{8}+\frac{1}{8}\right)+\left(\frac{32}{25}+\frac{2}{5}\right)+\frac{37}{100}+\frac{37}{12}\)
\(=\frac{9}{2}+\frac{42}{25}+\frac{37}{100}+\frac{37}{12}\)
\(=\left(\frac{9}{2}+\frac{37}{12}\right)+\left(\frac{42}{25}+\frac{37}{100}\right)\)
\(=\frac{91}{12}+\frac{41}{20}\)
\(=\frac{289}{30}\)
a)\(\frac{14}{35}\)
b)\(\frac{27}{449}\)
0.37 là 0x37 hay 0,37 vậy bn ?
\(a,\dfrac{1}{3}-\left(-1\dfrac{2}{5}\right)+\left(-3\dfrac{1}{4}\right)\\ =\dfrac{1}{3}-\left(-\dfrac{7}{5}\right)-\dfrac{13}{4}\\ =\dfrac{1}{3}+\dfrac{7}{5}-\dfrac{13}{4}\\ =\dfrac{20}{3\times20}+\dfrac{7\times12}{5\times12}-\dfrac{13\times15}{4\times15}\\ =\dfrac{20+84-195}{60}\\ =\dfrac{-91}{60}\)
\(b,\dfrac{5}{4}-\left(-3\dfrac{1}{2}\right)-\dfrac{7}{10}\\ =\dfrac{5}{4}+\dfrac{7}{2}-\dfrac{7}{10}\\ =\dfrac{5\times5}{4\times5}+\dfrac{7\times10}{2\times10}-\dfrac{7\times2}{10\times2}\\ =\dfrac{25+70-14}{20}\\ =\dfrac{81}{20}\)
\(c,\dfrac{3}{2}-\left[\left(-\dfrac{4}{7}-\left(\dfrac{1}{2}+\dfrac{5}{8}\right)\right)\right]\\ =\dfrac{3}{2}-\left[-\dfrac{4}{7}-\left(\dfrac{4}{8}+\dfrac{5}{8}\right)\right]\\ =\dfrac{3}{2}-\left(-\dfrac{4}{7}-\dfrac{9}{8}\right)\\ =\dfrac{3}{2}+\dfrac{4}{7}+\dfrac{9}{8}\\ =\dfrac{3\times28}{2\times28}+\dfrac{4\times8}{8\times7}+\dfrac{9\times7}{8\times7}\\ =\dfrac{84+32+63}{56}\\ =\dfrac{179}{56}\)
`@` `\text {Ans}`
`\downarrow`
`a,`
\(\dfrac{1}{3}-\left(-1\dfrac{2}{5}\right)+\left(-3\dfrac{1}{4}\right)\)
`= 1/3+7/5 - 13/4`
`= 26/15 - 13/4`
`= -91/60`
`b,`
\(\dfrac{5}{4}-\left(-3\dfrac{1}{2}\right)-\dfrac{7}{10}\)
`= 5/4+7/2 - 7/10`
`= 1,25 + 3,5 - 0,7`
`= 4,75 - 0,7`
`= 4,05`
`c,`
\(\dfrac{3}{2}-\left[\left(-\dfrac{4}{7}\right)-\left(\dfrac{1}{2}+\dfrac{5}{8}\right)\right]\)
`= 3/2 - [(-4/7) - 9/8]`
`= 3/2 - (-95/56)`
`= 179/56`
\(\frac{2}{5}\cdot5\frac{1}{4}-\frac{2}{7}\cdot3\frac{1}{4}\)
= \(\frac{2}{5}\cdot\frac{21}{4}-\frac{2}{7}\cdot\frac{13}{4}\)
= \(\frac{21}{10}-\frac{13}{14}\)
= \(\frac{41}{35}\)
\(\left(2\frac{1}{3}+3\frac{1}{2}\right):\left(-4\frac{1}{6}+3\frac{1}{7}\right)+7\frac{1}{2}\)
= \(\left(\frac{7}{3}+\frac{7}{2}\right):\left(\frac{-25}{6}+\frac{22}{7}\right)+\frac{15}{2}\)
= \(\frac{35}{6}:\frac{-43}{42}+\frac{15}{2}\)
= \(\frac{-245}{43}+\frac{15}{2}\)
= \(\frac{155}{86}\)
Hỗn số -3 5/7 được viết dưới dạng phân số bằng -16/7
\(-3\frac{5}{7}\) =\(\frac{\left(-3\right).7+5}{7}\) =\(\frac{-21+5}{7}\) =\(\frac{-16}{7}\)
= 2/3 + 1/3 . 7/18 : 5/12
= 2/3 + 7/54 : 5/12
= 2/3 + 14/45
= 44/45
Từ 2 đến 2011 có 2010 số hạng và 2012
= (2-3)+(4-5)+....+(2008-2009)+(2010-2011)+2012
= (-1)+(-1)+....+(-1)+(-1) +2012
Vì mỗi cặp 2 số => Có 1006 cặp
=(-1) x 1006 +2012
=1006+2012
=3018
\(\left(8x-32\right)⋮\left(x-5\right)\)
\(8\left(x-5\right)+8⋮\left(x-5\right)\)
Mà \(8\left(x-5\right)⋮\left(x-5\right)\)
\(8\left(x-5\right)+8⋮\left(x-5\right)\)
\(\Rightarrow8⋮\left(x-5\right)\)
\(\Rightarrow\left(x-5\right)\inƯ\left(8\right)=\left\{\pm1;\pm2;\pm4;\pm8\right\}\)
Tự kẻ bảng :)
\(3\dfrac{1}{5}\)=\(\dfrac{16}{5}\)
\(\dfrac{16}{5}\)