a,3/4 . (-5/12)+3/4.(-7/12)

` 3/4 . [ - ( 5/12 + 7/12  ) ] `

`3/4 . (-1) = -3/4 `

`2/3 . x - 0,5 = 3/4 `

`        x - 0,5 = 3/4 - 2/3 `

`        x-0,5 = 1/12 `

`        x =       1/12 + 0,5 `

`        x= 7/12 `

a, 3/4 . (-5/12)+3/4.(-7/12) 

= 3/4 . [(-5/12) + (-7/12)]

= 3/4 . (-1)

= -3/4

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a, 2/3 .x-0,5=3/4

2/3 . x = 3/2 + 0,5

2/3 . x = 2 

x = 2 : 2/3

x = 3 

vậy x = 3

Bài 2:

a: =>2/3x=3/4+1/2=3/4+2/4=5/4

=>x=5/4:2/3=5/4*3/2=15/8

b:=>-2x+4=3x-12

=>-5x=-16

=>x=16/5

\(\Leftrightarrow\dfrac{2}{3}x=0,5-\dfrac{7}{12}\Leftrightarrow x=-\dfrac{1}{2}:\dfrac{2}{3}\Leftrightarrow x=-\dfrac{3}{4}\)

\(\dfrac{1}{2}-\dfrac{2}{3}x=\dfrac{7}{12}\\ \dfrac{2}{3}x=\dfrac{13}{12}\\ x=\dfrac{39}{24}\)

\(0,5-\dfrac{2}{3}x=\dfrac{7}{12}\)

\(\dfrac{1}{2}-\dfrac{2}{3}x=\dfrac{7}{12}\)

\(\dfrac{2}{3}x=\dfrac{1}{2}-\dfrac{7}{12}\)

\(\dfrac{2}{3}x=-\dfrac{1}{12}\)

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

\(a.x+\dfrac{1}{6}=-\dfrac{3}{8}\)

\(\Leftrightarrow x=-\dfrac{13}{24}\)

\(b.2-\left(\dfrac{3}{4}-x\right)=\dfrac{7}{12}\)

\(\Leftrightarrow2-\dfrac{3}{4}+x=\dfrac{7}{12}\)

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

\(c.\dfrac{1}{2}x+\dfrac{1}{8}x=\dfrac{3}{4}\)

\(\Leftrightarrow\dfrac{5}{8}x=\dfrac{3}{4}\)

\(\Leftrightarrow x=\dfrac{6}{5}\)

\(d.75\%-1\dfrac{1}{2}+0,5:\dfrac{5}{12}-\left(\dfrac{-1}{2}\right)^2\)

\(=\dfrac{75}{100}-\dfrac{3}{2}+\dfrac{1}{2}:\dfrac{5}{12}-\dfrac{1}{4}\)

\(=-\dfrac{3}{4}+\dfrac{6}{5}-\dfrac{1}{4}\)

\(=\dfrac{1}{5}\)

a) \(x+\dfrac{1}{6}=\dfrac{-3}{8}\)

            \(x=\dfrac{-3}{8}-\dfrac{1}{6}\)

           \(x=\dfrac{-13}{24}\)

vậy x =....

b) \(2-\left(\dfrac{3}{4}-x\right)=\dfrac{7}{12}\)

             \(\dfrac{3}{4}-x=2-\dfrac{7}{12}\)

             \(\dfrac{3}{4}-x=\dfrac{17}{12}\)

                    \(x=\dfrac{3}{4}-\dfrac{17}{12}\)

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

vậy x =....

b. \(\dfrac{45}{100}:3-\dfrac{24,5}{100}:5\)

=\(0,45:3-0,245:5\)

= 0,15 - 0,049

= 0,101

c. 0,56 - \(\dfrac{12}{100}\)+ \(\dfrac{3}{4}-1\)

= 0,56 - 0,12 + 0,75 - 1

= 0,19

d. ( 0,4 x 7 - \(\dfrac{140}{100}\):0,5) x \(\left(\dfrac{2}{100}+\dfrac{4}{100}+\dfrac{6}{100}+...+1\right)\)

= (2,8 - 2,8 ) x (0,02 + 0,04 +0,06 +...+1)

=0

Không có câu A nha!

a, \(=16,24\left(12-3+1\right)\)

\(=16,24.10=162,4\)

b, \(=1,25\left(1+2+7\right)\)

\(=1,25.10=12,5\)

c, \(=2,46\left(2+8\right)\)

\(=2,46.10=24,6\)

\(a,=16,24\times12-16,24\times3+16,24\times1\\ =16,24\times\left(12-3+1\right)=16,24\times10=162,4\\ b,=1,25\times\left(1+2+7\right)=1,25\times10=12,5\)

a 16.24( 12-10+3)=16.24 x 5=81.2

b  1.25(1+2+7)=1.25 x 10= 12.5

c  2.46 x 2 + 2.46 x8 = 2.46(2 + 8)=2.46 x 10=24.6

học tốt

Giup minh voi

\(2\frac{2}{3}:x=1\frac{8}{9}:0,02\)

\(\frac{8}{3}:x=\frac{17}{9}:\frac{1}{50}\)

\(\frac{8}{3}:x=\frac{17}{9}.50\)

\(\frac{8}{3}:x=\frac{850}{9}\)

      \(x=\frac{8}{3}:\frac{850}{9}\)

      \(x=\frac{8}{3}x\frac{9}{850}\)

      \(x=\frac{12}{425}\)

Vậy \(x=\frac{12}{425}\)

\(-\frac{3}{5}:\frac{3}{14}+0,5.x=12\)