Tìm x, biết : a) -0,6 . x – 7/3 = 5,4 b) 2,8 : (1/5 – 3.x) = 1 2/5 07/08/2021 Bởi Melody Tìm x, biết : a) -0,6 . x – 7/3 = 5,4 b) 2,8 : (1/5 – 3.x) = 1 2/5
Đáp án: Giải thích các bước giải: a)-0,6 .x – $\frac{7}{3}$ =5,4 ⇒-0,6.x =$\frac{27}{5}$ +$\frac{7}{3}$ ⇒$\frac{-3}{5}$ .x =$\frac{116}{15}$ ⇒x =$\frac{-116}{9}$ b)2,8 :($\frac{1}{5}$ -3x )=1 $\frac{2}{5}$ ⇒$\frac{14}{5}$ :($\frac{1}{5}$ -3x ) =$\frac{7}{5}$ ⇒$\frac{14}{5}$ :$\frac{7}{5}$ =$\frac{1}{5}$ -3x ⇒ 2 =$\frac{1}{5}$ -3x ⇒ 3x =$\frac{-9}{5}$ ⇒ x =$\frac{-3}{5}$ Bình luận
a) $0,6.x-\dfrac{7}{3}=5,4$ $0,6x=5,4+\dfrac{7}{3}$ $0,6x=\dfrac{116}{15}$ $x=\dfrac{116}{15}:0,6$ $→x=\dfrac{116}{9}$ b) $2,8:(\dfrac{1}{5}-3x)=1\dfrac{2}{5}$ $2,8:(\dfrac{1}{5}-3x)=\dfrac{7}{5}$ $\dfrac{1}{5}-3x=2,8:\dfrac{7}{5}$ $\dfrac{1}{5}-3x=2,8.\dfrac{5}{7}=2$ $3x=\dfrac{1}{5}-2$ $3x=-\dfrac{9}{5}$ $x=-\dfrac{9}{5}:3=-\dfrac{9}{5}.\dfrac{1}{3}$ $→x=-\dfrac{3}{5}$ Bình luận
Đáp án:
Giải thích các bước giải:
a)-0,6 .x – $\frac{7}{3}$ =5,4
⇒-0,6.x =$\frac{27}{5}$ +$\frac{7}{3}$
⇒$\frac{-3}{5}$ .x =$\frac{116}{15}$
⇒x =$\frac{-116}{9}$
b)2,8 :($\frac{1}{5}$ -3x )=1 $\frac{2}{5}$
⇒$\frac{14}{5}$ :($\frac{1}{5}$ -3x ) =$\frac{7}{5}$
⇒$\frac{14}{5}$ :$\frac{7}{5}$ =$\frac{1}{5}$ -3x
⇒ 2 =$\frac{1}{5}$ -3x
⇒ 3x =$\frac{-9}{5}$
⇒ x =$\frac{-3}{5}$
a) $0,6.x-\dfrac{7}{3}=5,4$
$0,6x=5,4+\dfrac{7}{3}$
$0,6x=\dfrac{116}{15}$
$x=\dfrac{116}{15}:0,6$
$→x=\dfrac{116}{9}$
b) $2,8:(\dfrac{1}{5}-3x)=1\dfrac{2}{5}$
$2,8:(\dfrac{1}{5}-3x)=\dfrac{7}{5}$
$\dfrac{1}{5}-3x=2,8:\dfrac{7}{5}$
$\dfrac{1}{5}-3x=2,8.\dfrac{5}{7}=2$
$3x=\dfrac{1}{5}-2$
$3x=-\dfrac{9}{5}$
$x=-\dfrac{9}{5}:3=-\dfrac{9}{5}.\dfrac{1}{3}$
$→x=-\dfrac{3}{5}$