2/3 x X = 1/4        X x 1/5 = 1/2        X : 7/8 = 2/3

X = 1/4 : 2/3         X = 1/2 : 1/5         X = 2/3 x 7/8

X = 3/8                 X = 5/2                 X = 7/12

chúc bạn học tôt

nhanh lên các bạn tớ đang vội

very good

`4 1/2 xx x - 2 1/2 xx x = 1 1/2`

`=> 9/2 xx x - 5/2 xx x = 3/2`

`=> (9/2-5/2)xx x=3/2`

`=>4/2xx x=3/2`

`=>x=3/2:4/2`

`=>x=3/2:2`

`=>x=3/2xx1/2`

`=>x=3/4`

Vậy `x=3/4`

__

`x xx1/2+x xx1/3=5/6`

`=>x xx(1/2+1/3)=5/6`

`=>x xx(3/6+2/6)=5/6`

`=>x xx5/6=5/6`

`=>x=5/6:5/6`

`=>x=5/6xx6/5`

`=>x=1`

a: \(\Leftrightarrow\left[{}\begin{matrix}3x+2=4\\3x+2=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{2}{3}\\x=-2\end{matrix}\right.\)

a) \(x=-\dfrac{3}{5}\times\dfrac{9}{7}=-\dfrac{27}{35}\)

b) \(x\left(0,4-\dfrac{1}{5}\right)=\dfrac{3}{4}\)

\(x=\dfrac{3}{4}:\dfrac{1}{5}=\dfrac{15}{4}\)

a, \(x=-3,5.\dfrac{9}{7}=-\dfrac{9}{2}\)

b, \(\dfrac{2}{5}x-\dfrac{1}{5}x=\dfrac{3}{4}\Leftrightarrow\dfrac{1}{5}x=\dfrac{3}{4}\Leftrightarrow x=\dfrac{3}{4}:\dfrac{1}{5}=\dfrac{15}{4}\)

x=\(\dfrac{9}{7}x-3.5\)

x=\(\dfrac{-9}{5}\)

tớ  chưa học xin lỗi

\(\frac{4}{7}+x\times2=\frac{5}{3}\)

           \(x\times2=\frac{5}{3}-\frac{4}{7}\)

           \(x\times2=\frac{23}{21}\)

                    \(x=\frac{23}{21}:2\) 

                     \(x=\frac{23}{42}\)

\(\frac{4}{7}+x\times2=\frac{5}{3}\)

          \(x\times2=\frac{5}{3}-\frac{4}{7}\)

           \(x\times2=\frac{23}{21}\)

                   \(x=\frac{23}{21}:2\)

                   \(x=\frac{23}{42}\)

Vậy x = 23/42

x*2=5/3-4/7

x*2=23/21

x   =23/21:2

x   =23/42

theo dõi giúp mik nhé^^

:v

........cạn lời

nhiều lắm rồi

\(a,\left(\dfrac{31}{35}-\dfrac{4}{7}\right)\times\dfrac{8}{7}:2\\ =\left(\dfrac{31}{35}-\dfrac{4\times5}{35}\right)\times\dfrac{8}{7}:2\\ =\dfrac{11}{35}\times\dfrac{8}{7}:2\\ =\dfrac{88}{245}:2\\ =\dfrac{44}{245}\\ b,\left(1-\dfrac{1}{2}\right)\times\left(1-\dfrac{1}{3}\right)\times\left(1-\dfrac{1}{4}\right)\times\left(1-\dfrac{1}{5}\right)\\ =\left(\dfrac{2-1}{2}\right)\times\left(\dfrac{3-1}{3}\right)\times\left(\dfrac{4-1}{4}\right)\times\left(\dfrac{5-1}{5}\right)\\ =\dfrac{1}{2}\times\dfrac{2}{3}\times\dfrac{3}{4}\times\dfrac{4}{5}\\ =\dfrac{1}{3}\times\dfrac{3}{4}\times\dfrac{4}{5}\\ =\dfrac{1}{4}\times\dfrac{4}{5}=\dfrac{1}{5}\)

a, ( \(\dfrac{31}{35}\) - \(\dfrac{4}{7}\)) \(\times\) \(\dfrac{8}{7}\): 2

= \(\left(\dfrac{31}{35}-\dfrac{20}{35}\right)\) \(\times\) \(\dfrac{8}{7}\) : 2

= \(\dfrac{11}{35}\) \(\times\) \(\dfrac{8}{7}\) \(\times\) \(\dfrac{1}{2}\)

= \(\dfrac{44}{35}\) \(\times\) \(\dfrac{4}{7}\)

= \(\dfrac{44}{245}\)

b, ( 1 - \(\dfrac{1}{2}\)) \(\times\) ( 1 - \(\dfrac{1}{3}\)) \(\times\) ( 1 - \(\dfrac{1}{4}\)) \(\times\) ( 1 - \(\dfrac{1}{5}\))

= \(\dfrac{1}{2}\) \(\times\) \(\dfrac{2}{3}\) \(\times\) \(\dfrac{3}{4}\) \(\times\) \(\dfrac{4}{5}\)

= \(\dfrac{1}{5}\) \(\times\) \(\dfrac{2\times3\times4}{2\times3\times4}\)

= \(\dfrac{1}{5}\)