Question

bài 1 : tính

a) 1/7 : 5/17 - 3/2 . ( 1/6 - 7/12 )

b) 25/77 - ( 1/5 - 7/15 ) : 10/11 : |-3/4|

c) 4/7 + 15/4 - 11/4 + 3/7 - 1/2 + 1/3

bài 2 : tìm x

a) 3/4.x + 1/2 = -3/5

b) x-5/4 = 1/3 - 3/4 .x

c) -2/3 . ( x - 1/4 ) = 1/3 . ( 2x-1)

Answer 1

Bài 2: 

a: =>3/4x=-3/5-1/2=-11/10

\(\Leftrightarrow x=\dfrac{-11}{10}:\dfrac{3}{4}=\dfrac{-11}{10}\cdot\dfrac{4}{3}=-\dfrac{44}{30}=-\dfrac{22}{15}\)

b: \(\Leftrightarrow x+\dfrac{3}{4}x=\dfrac{1}{3}+\dfrac{5}{4}=\dfrac{19}{12}\)

=>7/4x=19/12

=>x=19/21

c: \(\Leftrightarrow-\dfrac{2}{3}x+\dfrac{1}{6}=\dfrac{2}{3}x-\dfrac{1}{3}\)

=>-4/3x=-1/3-1/6=-1/2

=>x=1/2:4/3=1/2x3/4=3/8

Answer 2

Bài 1 

\(\dfrac{1}{7}:\dfrac{5}{17}-\dfrac{3}{2}.\left(\dfrac{1}{6}-\dfrac{7}{12}\right)\)

\(\dfrac{1}{7}.\dfrac{17}{5}-\dfrac{3}{2}.\left(-\dfrac{5}{12}\right)\)

\(\dfrac{17}{35}-\left(-\dfrac{5}{8}\right)\)

\(\dfrac{17}{35}+\dfrac{5}{8}\) 

\(\dfrac{311}{280}\)