cho ket qua thi duoc chu dai ra dai dong lam  ma minh cung dang gap lam ne ban co la ket qua khong

cho kết quả thôi cũng dc a~~

`@` `\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`

`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`

1)1/6 - - 5/6 = 1/6 + 5/6 = 1

2)6/13 - -14/39 = 6/13 + 14/39= 32/39

3)4/5 - 4/-18 = 4/5 + 4/18= 46/45

4)7/21 - 9/-36 = 7/21 + 9/36 = 7/12

5)-12/18 - -21/35  = -12/18 + 21/35 = -1/15

6)-3/21 - 6/42 = -2/7

7)-18/24 - 15/21 = -41/28

8)1/6 - 2/5 =-7/30

c) Ta có: \(\dfrac{3}{5}+\dfrac{-5}{20}+\dfrac{30}{75}+\dfrac{-7}{4}\)

\(=\dfrac{3}{5}+\dfrac{2}{5}+\dfrac{-1}{4}+\dfrac{-7}{4}\)

\(=1-2=-1\)

Giải:

a)-1/12+4/3=-1/12+16/12=15/12=5/4

b)(-4/14-3/15)-(1/5-20/35-(-1)).7

=-17/35-22/35.7

=-17/35-22/5

=-171/35

c)3/5+-5/20+30/75+-7/4

=3/5+-1/4+2/5+-7/4

=(3/5+2/5)+(-1/4+-7/4)

=1+-2

=-1

d)5/6.-12/14+7/13

=-5/7+7/13

=-16/91

e)2/-9-5/-36-1/4

=-1/12-1/4

=-1/3

f)2/23+-5/12+7/18+21/23+-7/12

=(2/23+21/23)+(-5/12+-7/12)+7/18

=1+-1+7/18

=7/18

12) 17 – 11 – 14 – (-39)

=17-11-14+39

=6-14+39

=-8+39

=31

13) −127 - 18.( 5 - 6)

=-127-18.1

=-145
14) 100 + (+430) + 2145 + (-530)

=530+2145-530

=(530-530)+2145

=0+2145

=2145
15) (+12).13 + 13.(-22)

=13.[12+(-22)]

=13.(-10)

=-130
16) {[14 : (-2)] + 7} : 2012

={-7+7}:2012

=0:2012

=0
17) 13 – 18 – (- 42) - 15

=13-18+42-15

=-5+42-15

=37-15

=22
18) 369 – 4[(-5) + 4.(-8)]

=369-4[-5+(-32)]

=369-4(-37)

=369+148

=517
19) (-12).(-13) +13.(-29)

=12.13+13.(-29)=13.[12+(-29)]=13.(-17)=-221

20) 125 – 4[ 3 – 7.(-2) ]

=125-4[3+14]

=125-4.17

=125-68

=57
21) (-14).9 – 13.(-9)

=(-14).9+13.9

=9.[-14+13]

=9.(-1)

=-9

âm 9 nha bạn
 

a; \(\dfrac{9}{4}\) - \(\dfrac{-11}{4}\)

= \(\dfrac{9}{4}\) + \(\dfrac{11}{4}\)

= \(\dfrac{20}{4}\)

= 5 

b; \(\dfrac{7}{8}\) - \(\dfrac{3}{-8}\) - \(\dfrac{1}{8}\)

=  \(\dfrac{7}{8}\) + \(\dfrac{3}{8}\) - \(\dfrac{1}{8}\)

= \(\dfrac{7+3-1}{8}\)

= \(\dfrac{9}{8}\) 

c; \(\dfrac{-5}{21}\) - \(\dfrac{25}{21}\) - \(\dfrac{-1}{21}\)

  = \(\dfrac{-5}{21}\) - \(\dfrac{25}{21}\) + \(\dfrac{1}{21}\)

 =  \(\dfrac{-5-25+1}{21}\)

= \(\dfrac{-29}{21}\)

\(\dfrac{1}{2}+\dfrac{3}{5}+\dfrac{3}{4}+\dfrac{7}{25}=\left(\dfrac{2}{4}+\dfrac{3}{4}\right)+\left(\dfrac{15}{25}+\dfrac{7}{25}\right)=\dfrac{5}{4}+\dfrac{22}{25}=\dfrac{125}{100}+\dfrac{88}{100}=\dfrac{213}{100}=2\dfrac{13}{100}\)

\(\dfrac{1}{2}+\dfrac{3}{5}+\dfrac{7}{25}+\dfrac{3}{4}=\dfrac{11}{10}+\dfrac{7}{25}+\dfrac{3}{4}\)

                             \(=\dfrac{69}{50}+\dfrac{3}{4}\)

                             \(=\dfrac{213}{100}\)

a: =>x=7-20=-13

b: =>x=-18+12=-6

c: =>x=9 hoặc x=-6

d: =>x=0 hoặc x=4

e: =>6-x=13-3+14=24

=>x=-18

Câu g và h đề thiếu rồi bạn