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12 tháng 1 2019

a,1+2+3+5+8+13+21+34+55+89=231

b,1+7+8+15+23+38+61+99+160=412

k mình nhé

Học giỏi

a, 1+2+3+5+8+13+21+34+55+89

=231

b,1+7+8+15+23+38+61+99+160

=412

Theo mik viết thêm vài số là đc

`@` `\text {Ans}`

`\downarrow`

`1,`

`a)`

`-7/25 + (-8)/25`

`= (-7 - 8)/25`

`= -15/25`

`= -3/5`

`b)`

`6/13 + (-15)/39`

`= 18/39 + (-15)/39`

`= (18 - 15)/39`

`= 3/39`

`= 1/13`

`c)`

`5/7 + 4/(-14)`

`= 10/14 + (-4)/14`

`= (10 - 4)/14`

`= 6/14`

`= 3/7`

`d)`

`-8/18 + (-15)/27`

`= -4/9 + (-5)/9`

`= (-4-5)/9`

`= -9/9 = -1`

20 tháng 7 2023

`2,`

`a)`

`3/5 + (-7)/4`

`= 12/20 + (-35)/20`

`= (12 - 35)/20`

`=-23/20`

`b)`

`(-2) + (-5)/8`

`= (-16)/8 + (-5)/8`

`= (-16 - 5)/8`

`= -21/8`

`c)`

`1/8 + (-5)/9`

`= 9/72 + (-40)/72`

`= (9-40)/72`

`= -31/72`

`d)`

`6/13 + (-14)/39`

`= 18/39 + (-14)/39`

`= (18 - 14)/39`

`= 4/39`

`e)`

`(-18)/24 + 15/21`

`= (-3)/4 + 5/7`

`= (-21)/28 + 20/28`

`= (-21 + 20)/28`

`= -1/28`

2 tháng 5 2023

a)( \(\dfrac{-8}{40}\)+\(\dfrac{25}{40}\))+(\(\dfrac{-3}{8}\))

=\(\dfrac{17}{40}\)+(\(\dfrac{-3}{8}\))

=\(\dfrac{17}{40}\)+(\(\dfrac{-15}{40}\))

=\(\dfrac{2}{40}\)

=\(\dfrac{1}{20}\)

b)\(\dfrac{-5}{21}\)-(\(\dfrac{16}{21}\)-\(\dfrac{21}{21}\))

=\(\dfrac{-5}{21}\)-\(-5\)

=\(\dfrac{-25}{105}\)-\(\dfrac{-105}{105}\)

=\(\dfrac{16}{21}\)

bằng đây thôi nha mỏi tay quá

c: =3/7(-5/11+6/11)=3/7*1/11=3/77

d:=8/-3(4/3-7/3)=8/3

e: =3,4-5/8-0,4-3/8

=2-1

=1

25 tháng 6 2023

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

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

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

`@` `\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`

a: =-12/20+5/20-6/20

=-13/20

b: =10/50-45/50-14/50

=-49/50

c: =31/23-7/32-8/23=1-7/32=25/32

24 tháng 4 2023

`a)-3/5 + 1/4 + -3/10= (-12)/20 + 5/20 + (-6)/20 = -13/20` 

 

`b)1/5 + -9/10 + (-7/25)= 10/50 + (-45)/50 + (-14)/50 = (-49)/50`

 

`c)31/23 - ( 7/32 + 8/23 )=  31/23 - 417/736 =992/736 - 417/736  =  575/736=25/32  `

 

 

a: =1/6+14/6-3/6=12/6=2

b: =-13/8+5/4:(-5/4)

=-13/8-1=-21/8

c: =-3/8(2/5+14/5)

=-3/8*16/5

=-6/5

d: =5/34(1/4+11/9-2/9+29/4)

=5/34*(15/2+1)

=5/34*17/2
=5/4

8 tháng 11 2021

a,4/5+1/6
=29/30

b,7/12+2-1/4
=31/12-1/4
=7/3

17 tháng 4 2021

ngu

17 tháng 4 2021

ko giải đc thì đi ra chỗ khác

Bài 1: 

Ta có: \(x-35\%\cdot x=\dfrac{1}{25}\)

\(\Leftrightarrow65\%\cdot x=\dfrac{1}{25}\)

\(\Leftrightarrow x=\dfrac{1}{25}:\dfrac{13}{20}=\dfrac{1}{25}\cdot\dfrac{20}{13}=\dfrac{4}{65}\)

Vậy: \(x=\dfrac{4}{65}\)

Bài 2: 

a) Ta có: \(17\dfrac{2}{31}-\left(\dfrac{15}{17}+6\dfrac{2}{31}\right)\)

\(=17\dfrac{2}{31}-\dfrac{15}{17}-6\dfrac{2}{31}\)

\(=11+\dfrac{2}{31}-\dfrac{15}{17}\)

\(=\dfrac{5366}{527}\)