bài 1)
( 1/3 + 5/2) . -5/6 + 1/2 = 17/6 . -67/36
( 15/4 - 10/4) . 2/5 + 1/2 = 5/4 . 2/5 + 1/2 = 1
bài 2)
a) x = 1 3/8 - 0,25
x = 1,125
b) 4/5.x - 3/4 = -9/2
4/5 .x = -9/2 + 3/4
4/5.x = -15/4
x = -15/4 : 4/5
x = -75/16
Bài 1.
a) \(\dfrac{1}{2}+\dfrac{1}{3}.\dfrac{-5}{6}+\dfrac{-5}{6}.\dfrac{5}{2}\)
\(=\dfrac{1}{2}+\dfrac{-5}{6}\left(\dfrac{1}{3}+\dfrac{5}{2}\right)\\ =\dfrac{1}{2}+\dfrac{-5}{6}.\dfrac{17}{6}=\dfrac{1}{2}-\dfrac{85}{36}=-\dfrac{67}{36}\)
b) \(\dfrac{2}{5}.\dfrac{15}{4}-\dfrac{2}{5}.\dfrac{10}{4}+\dfrac{1}{2}\)
\(=\dfrac{2}{5}\left(\dfrac{15}{4}-\dfrac{10}{4}\right)+\dfrac{1}{2}\\ =\dfrac{2}{5}.\dfrac{5}{4}+\dfrac{1}{2}=\dfrac{1}{2}+\dfrac{1}{2}=1\)
bài 1)
( 1/3 + 5/2) . -5/6 + 1/2 = 17/6 . -67/36
( 15/4 - 10/4) . 2/5 + 1/2 = 5/4 . 2/5 + 1/2 = 1
bài 2)
a) x = 1 3/8 - 0,25
x = 1,125
b) 4/5.x - 3/4 = -9/2
4/5 .x = -9/2 + 3/4
4/5.x = -15/4
x = -15/4 : 4/5
x = -75/16
