$a) 5x .(x-1/3) = 0$
$⇒$ \(\left[ \begin{array}{l}x=0\\x=\dfrac{1}{3}\end{array} \right.\)
Vậy $x$ $∈$ `{0;\frac{1}{3}}`
`b) (x+1/4) . (x-3/7) = 0`
$⇒$ \(\left[ \begin{array}{l}x=\dfrac{-1}{4}\\x=\dfrac{3}{7}\end{array} \right.\)
Vậy $x$ $∈$ `{\dfrac{-1}{4}; \dfrac{3}{7}}`
$c)1+3x =-5$
$⇔ 3x = -6$
$⇔ x = -2$
Vậy $x=-2$
$d$ $1,5x - 2\dfrac{1}{3}.x = 1.5 - \dfrac{2}{3}$
$⇔ x( \dfrac{3}{2} - \dfrac{7}{3}) = 5 - \dfrac{2}{3}$
$⇔ x . \dfrac{-5}{6} = \dfrac{13}{3}$
$⇔ x = \dfrac{-26}{5}$
Vậy $x = \dfrac{-26}{5}$
$e$) `2/3 + 1/3 : x = 3/5`
$⇔$ `1/3 : x = 3/5 - 2/3`
$⇔$ `1/3 : x = {-1}/15`
$⇔$ `x = 1/3 . (-15)`
$⇔$ `x = -5`
Vậy $x=-5$
$g$) ` ({2x}/3 - 3) : (-10)= 2/5`
$⇒$ `{2x}/3 - 3 = -4`
$⇔$ `{2x}/3 = 7`
$⇔$ `2x = 21`
$⇔$ $x = \dfrac{21}{2}$
Vậy $x = \dfrac{21}{2}$
