a) x-2/3=7/12 b) x/4-3/20=1/5 c) 1/3.x-0,5.x=3/4

2 bình luận về “a) x-2/3=7/12 b) x/4-3/20=1/5 c) 1/3.x-0,5.x=3/4”

1. a) x – 2/3 = 7/12

   => x = 7/12 + 2/3

   => x = 5/4

   Vậy x = 5/4

   b) x/4 – 3/20 = 1/5

   => x/4 = 1/5 + 3/20

   => x/4 = 7/20

   => frac{5x}{20} = 7/20

   => 5x = 7

   => x = 5/7

   Vậy x = 5/7

   c) 1/3 . x – 0,5 . x = 3/4

   => 1/3 . x – 1/2 . x = 3/4

   => (1/3 – 1/2) x = 3/4

   => (-1/6) x = 3/4

   => x = 3/4 : (-1/6)

   => x = -9/2

   Vậy x = -9/2

   Trả lời
2. a) $x$ – $\frac{2}{3}$ = $\frac{7}{12}$ 

   ⇔ $x$ = $\frac{7}{12}$ + $\frac{2}{3}$

   ⇔ $x$ = $\frac{7}{12}$ + $\frac{8}{12}$ = $\frac{15}{12}$ = $\frac{5}{4}$

   b) $\frac{x}{4}$ – $\frac{3}{20}$ = $\frac{1}{5}$

   ⇔ $5x$ – $3$ = $4$ ( quy đồng khử mẫu)

   ⇔ $5x$ = $7$

   ⇒ $x$ = $\frac{7}{5}$

   c) $\frac{1}{3}$ . $x$ – $0,5x$ = $\frac{3}{4}$

   ⇔ $\frac{1}{3}$ . $x$ – $\frac{1}{2}$. $x$ = $\frac{3}{4}$

   ⇔ $\frac{5}{6}$ . $x$ = $\frac{3}{4}$

   ⇒ $x$ = $\frac{3}{4}$ ÷ $\frac{5}{6}$

   ⇒ $x$ = $\frac{18}{20}$ = $\frac{9}{10}$

   Trả lời