1. Tìm x a) 7/3 – ( x + 5/3 ) = -12/5 2. Tính a) -25/13 + ( -9/17) + 12/13 + (-25/17) b) 2/3 + -1/-4 + 1/21 + 1/12

Bài 1:

$\frac{7}{3}$ – ( x + $\frac{5}{3}$ ) = $\frac{-12}{5}$

⇒ $\frac{7}{3}$ – x – $\frac{5}{3}$ =  $\frac{-12}{5}$

⇒ $\frac{2}{3}$  – x =  $\frac{-12}{5}$

⇒ x = $\frac{2}{3}$ – $\frac{-12}{5}$

⇒ x = $\frac{46}{15}$ 

Vậy x = $\frac{46}{15}$

Bài 2: 

a)  $\frac{-25}{13}$ + ($\frac{-9}{17}$) + $\frac{12}{13}$ + ($\frac{-25}{17}$)

= ( $\frac{-25}{13}$ + $\frac{12}{13}$) + [ $\frac{-9}{17}$ + ($\frac{-25}{17}$) ]

= – 1 + ( -2 )

= -3

b)  $\frac{2}{3}$ + $\frac{-1}{-4}$ + $\frac{1}{21}$ + $\frac{1}{12}$ 

= ( $\frac{2}{3}$ + $\frac{1}{21}$ ) +  ( $\frac{-1}{-4}$ + $\frac{1}{12}$ )

= $\frac{5}{7}$  +  $\frac{1}{3}$ 

= $\frac{22}{21}$ 

#Chúc bạn 1 ngày tốt lành !!