Bài 1:
a) \(\dfrac{2}{3}\)-\((\dfrac{-5}{7}\)+\(\dfrac{8}{3}\))
b) \(\dfrac{1}{5}\). \(\dfrac{4}{7}\)+\(\dfrac{3}{7}\).\(\dfrac{1}{5}\)-\(\dfrac{1}{5}\)
c) 30% - (\(2\dfrac{3}{4}\)-3,25) : \(\dfrac{5}{2}\)
d) (1,3 1,6 + 1,9 + +...+ 7,0 + 7,3) :...
Đọc tiếp
Bài 1:
a) \(\dfrac{2}{3}\)-\((\dfrac{-5}{7}\)+\(\dfrac{8}{3}\))
b) \(\dfrac{1}{5}\). \(\dfrac{4}{7}\)+\(\dfrac{3}{7}\).\(\dfrac{1}{5}\)-\(\dfrac{1}{5}\)
c) 30% - (\(2\dfrac{3}{4}\)-3,25) : \(\dfrac{5}{2}\)
d) (1,3 1,6 + 1,9 + +...+ 7,0 + 7,3) : (-0,1)3
b) 
d) 
\(a,\dfrac{2}{3}-\left(\dfrac{-5}{7}+\dfrac{8}{3}\right)=\left(\dfrac{2}{3}-\dfrac{8}{3}\right)+\dfrac{5}{7}\\ =-\dfrac{6}{3}+\dfrac{5}{7}=\dfrac{5}{7}-2=\dfrac{5-2.7}{7}=\dfrac{5-14}{7}=-\dfrac{9}{7}\\ --\\ b,\dfrac{1}{5}.\dfrac{4}{7}+\dfrac{3}{7}.\dfrac{1}{5}-\dfrac{1}{5}=\dfrac{1}{5}.\left(\dfrac{4}{7}+\dfrac{3}{7}-1\right)=\dfrac{1}{5}.0=0\)
\(c,30\%-\left(2\dfrac{3}{4}-3,25\right):\dfrac{5}{2}\\ =30\%-\left(2,75-3,25\right):2,5\\ =0,3-0,5:2,5\\ =0,3-0,5=-0,2\\ --\\ d,\left(1,3+1,6+1,9+...+7,0+7,3\right):\left(-0,1\right)^3\\ =\left[\left(7,3-1,3\right):\left(1,6-1,3\right)+1\right]:2.\left(7,3+1,3\right):\left(-0,001\right)\\ =-90300\)