Đáp án:
$\text{a) ( $\dfrac{1}{7}$x - $\dfrac{2}{7}$) .(-$\dfrac{1}{5}$x + $\dfrac{3}{5}$).($\dfrac{1}{3}$x +$\dfrac{4}{3}$) =0 }$
$\text{⇔ $\dfrac{1}{7}$x - $\dfrac{2}{7}$ = 0 ⇔ x = 2 }$
$\text{⇔ -$\dfrac{1}{5}$x + $\dfrac{3}{5}$ = 0 ⇔ x= 3 }$
$\text{⇔ $\dfrac{1}{3}$x + $\dfrac{4}{3}$ = 0 ⇔ x = -4 }$
$\text{Vậy x ∈ { 2 ; 3 ; -4} }$
$\text{b) $\dfrac{1}{6}$x + $\dfrac{1}{10}$x - $\dfrac{4}{15}$ + 1 =0 }$
$\text{⇔ $\dfrac{10}{60}$x + $\dfrac{6}{60}$x - $\dfrac{16}{60}$x + $\dfrac{60}{60}$ = 0 }$
$⇔ 10x + 6x - 16x + 60=0$
$⇔ 0x + 60 = 0$
$⇔ 0x= -60 (vô lí)$
$\text{Vậy x ∈ {∅} }$
