a, ( 4,578 x 3 +5,422 x 3 ) : 1,2 -1,2

 = [ 3 x ( 4,578 +5,422 ) ]  : 1,2 -1,2

 = ( 3 x 10 ) : 1,2 -1,2

 = 30  : 1,2 -1,2

 = 25 -1,2 

 = 23,8 

b, \(\frac{3}{5}\)x\(\frac{9}{7}\)-\(\frac{3}{5}\)x\(\frac{3}{14}\)

= \(\frac{3}{5}\)x ( \(\frac{9}{7}\)- \(\frac{3}{14}\)) 

= \(\frac{3}{5}\)x\(\frac{15}{14}\)

= \(\frac{9}{14}\)

Chúc bạn học tốt

(4,578 x 3 + 5,422 x 3 ) : 1,2 - 1,2

=( 3 x [4,578 + 5,422 ] : 1,2 - 1,2

=(3 x 10) : 1,2 - 1,2

=30 : 1,2 - 1,2

=25-1.2

=23.8

a) 23,8

b)45/70

a: =>x-22=9

hay x=31

= 51/20

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= 3/14

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= 4/7 - 2/7 

= 2/7

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= 17/45

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= 2/3 

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= 2 x 1/4 

= 1/2

\(\frac{4}{5}\)+ \(\frac{1}{5}\): \(\frac{-2}{15}\)= \(\frac{4}{5}\)+ \(\frac{1}{5}\)* \(\frac{-15}{2}\)=\(\frac{4}{5}\) + \(\frac{-3}{2}\)= \(\frac{-7}{10}\)

b = \(\frac{-7}{12}\). (\(\frac{3}{11}\)+ \(\frac{-14}{11}\)) + \(\frac{5}{6}\)= \(\frac{-7}{12}\). (-1) + \(\frac{5}{6}\)= \(\frac{7}{12}\)+ \(\frac{10}{12}\)= \(\frac{17}{12}\)

x-\(\frac{3}{5}\)x = \(\frac{2}{5}\)

=> x.(1-\(\frac{3}{5}\)) =\(\frac{2}{5}\)

=> x. \(\frac{2}{5}\)= \(\frac{2}{5}\)

=> x=1

Vậy x=1

\(a,-\dfrac{12}{16}-\left(\dfrac{3}{4}-x\right)=-\dfrac{5}{3}\)

\(\dfrac{3}{4}-x=-\dfrac{12}{16}-\left(-\dfrac{5}{3}\right)\)

\(\dfrac{3}{4}-x=\dfrac{11}{12}\)

\(x=\dfrac{3}{4}-\dfrac{11}{12}\)

\(x=-\dfrac{1}{6}\)

\(b,x-\dfrac{3}{7}:\dfrac{9}{14}=-\dfrac{7}{3}\)

\(x-\dfrac{3}{7}=-\dfrac{7}{3}\times\dfrac{9}{14}\)

\(x-\dfrac{3}{7}=-\dfrac{3}{2}\)

\(x=-\dfrac{3}{2}+\dfrac{3}{7}\)

\(x=-\dfrac{15}{14}\)

\(c,-\dfrac{3}{4}x+\dfrac{5}{8}x=\dfrac{1}{3}\)

\(\left(-\dfrac{3}{4}+\dfrac{5}{8}\right)x=\dfrac{1}{3}\)

\(-\dfrac{1}{8}x=\dfrac{1}{3}\)

\(x=\dfrac{1}{3}:\left(-\dfrac{1}{8}\right)\)

\(x=-\dfrac{8}{3}\)

`-12/16 - ( 3/4 - x ) = -5/3`

`=> 3/4 - x=-12/16 -(-5/3)`

`=> 3/4 - x=-12/16 +5/3`

`=> 3/4 - x=11/12`

`=> x= 3/4-11/12`

`=> x=9/12 -11/12`

`=> x=-1/6`

__

`x - 3/7 : 9/14 = - 7/3`

`=>x - 3/7=-7/3 xx 9/14`

`=>x - 3/7=-3/2`

`=>x= -3/2 + 3/7`

`=>x=-15/14`

__

`-3/4 x + 5/8 x =1/3`

`=> (-3/4 + 5/8) x =1/3`

`=> ( -6/8+ 5/8) x =1/3`

`=> -1/8 x=1/3`

`=>x= 1/3 : (-1/8)`

`=> x= 1/3 xx (-8)`

`=>x= -8/3`

( 48 x 5 + 48 x 7 - 48 x 12 )

=48 x ( 5 + 7 - 12 )

=48 x 0

= 0

\(\Rightarrow\)( 48 x 5 + 48 x 7 - 48 x 12 ) : ( 1 + 3 + 5 + 7 +.....+ 91 ) = 0

Hk tốt

      \(\left(48\text{ x }5+48\text{ x }7-48\text{ x }12\right)\text{ : }\left(1+3+5+7+...+91\right)\)

\(=\left(48\text{ x }5+48\text{ x }7-48\text{ x }12\right)\text{ : }A\)

\(=48\text{ x }\left(5+7-12\right)\text{ : }A\)

\(=48\text{ x }\left(12-12\right)\text{ : }A\)

\(=48\text{ x }0\text{ : }A\)

\(=0\text{ : }A\)

\(=0\)

(48 x 5+48 x 7 -48 x12):(1+3+5+7+...+91)

=(48x12-48x12):(91+1)x45:2

=0:2070

=0

lần lượt là:3920

6000

5600

6100

Bạn ơi bạn làm đc bao nhiêu thì làm phụ mình nhé 

bài1

a, 

5 - 7 + 3 +(-8)

= -2 + 3 + ( - 8)

=     1    + (-8)= -7

a; - (-5) - (+7) + (+3) + (-8)

  = 5 - 7 + 3  - 8

= (5 + 3 - 8) - 7

= (8 - 8) - 7

= 0 - 7

= - 7