4/5

\(0,8=\dfrac{8}{10}=\dfrac{4}{5}\)

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 ?

Mấy bài này dài với số lượng nhiều nên bn ưu tiên việc tách ra thì sẽ có người trả lời đấy ạ !

vậy bạn có thể trả lời giúp tui bài 3 3 câu đầu đk ạ

\(a,\dfrac{1}{3}-\left(-1\dfrac{2}{5}\right)+\left(-3\dfrac{1}{4}\right)\\ =\dfrac{1}{3}-\left(-\dfrac{7}{5}\right)-\dfrac{13}{4}\\ =\dfrac{1}{3}+\dfrac{7}{5}-\dfrac{13}{4}\\ =\dfrac{20}{3\times20}+\dfrac{7\times12}{5\times12}-\dfrac{13\times15}{4\times15}\\ =\dfrac{20+84-195}{60}\\ =\dfrac{-91}{60}\)

\(b,\dfrac{5}{4}-\left(-3\dfrac{1}{2}\right)-\dfrac{7}{10}\\ =\dfrac{5}{4}+\dfrac{7}{2}-\dfrac{7}{10}\\ =\dfrac{5\times5}{4\times5}+\dfrac{7\times10}{2\times10}-\dfrac{7\times2}{10\times2}\\ =\dfrac{25+70-14}{20}\\ =\dfrac{81}{20}\)

\(c,\dfrac{3}{2}-\left[\left(-\dfrac{4}{7}-\left(\dfrac{1}{2}+\dfrac{5}{8}\right)\right)\right]\\ =\dfrac{3}{2}-\left[-\dfrac{4}{7}-\left(\dfrac{4}{8}+\dfrac{5}{8}\right)\right]\\ =\dfrac{3}{2}-\left(-\dfrac{4}{7}-\dfrac{9}{8}\right)\\ =\dfrac{3}{2}+\dfrac{4}{7}+\dfrac{9}{8}\\ =\dfrac{3\times28}{2\times28}+\dfrac{4\times8}{8\times7}+\dfrac{9\times7}{8\times7}\\ =\dfrac{84+32+63}{56}\\ =\dfrac{179}{56}\)

`@` `\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

\(a,\dfrac{1}{2}-\dfrac{1}{3}-\left(-\dfrac{5}{4}\right)=\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{5}{4}=\dfrac{1\times6-1\times4+5\times3}{12}=\dfrac{6-4+15}{12}=\dfrac{17}{12}\\ b,\dfrac{5}{4}-\dfrac{1}{2}-\dfrac{7}{8}=\dfrac{5\times2-1\times4-7}{8}=\dfrac{10-4-7}{8}=-\dfrac{1}{8}\\ c,\dfrac{1}{5}-\dfrac{1}{2}+\dfrac{9}{10}=\dfrac{1\times2-1\times5+9}{10}=\dfrac{2-5+9}{10}=\dfrac{6}{10}=\dfrac{3}{5}\\ d,\dfrac{5}{4}-\dfrac{1}{3}+\dfrac{7}{6}=\dfrac{5\times3-1\times4+7\times2}{12}=\dfrac{15-4+14}{12}=\dfrac{25}{12}\)

`1/2+(-1/3)-(-5/4)`

`=1/2-1/3+5/4`

`=3/6-2/6+5/4`

`=1/6+5/4`

`=2/12+15/12`

`=17/12`

__

`5/4-1/2+(-7/8)`

`=5/4-1/2-7/8`

`=10/8-4/8-7/8`

`=6/8-7/8`

`=-1/8`

__

`1/5-1/2+9/10`

`=2/10-5/10+9/10`

`=-3/10+9/10`

`=6/10`

`=3/5`

__

`5/4-1/3+7/6`

`=15/12-4/12+14/12`

`=11/12+14/12`

`=25/12`

`#lv`

4:

a: =4/15-2,9+11/15=1-2,9=-1,9

b: \(=-36,75+3,7-63,25+6,3=10-100=-90\)

c: \(=6,5+3,5-\dfrac{10}{17}-\dfrac{7}{17}=10-1=9\)

d: \(=\dfrac{13}{25}\left(-39,1-60,9\right)=\dfrac{13}{25}\left(-100\right)=-52\)

e: =-5/12-7/12-3,7-6,3=-1-10=-11

f: =2,8(-6/13-7/13)-7,2=-2,8-7,2=-10

cậu tách ra từng bài thôi nha.