Ngoặc vuông nha

Ngoặc vuông nha

4 giờ 20 phút = 260 phút

5 giờ kém 20 phút hay 4 giờ 40 phút = 280 phút

=> 4 giờ 20 phút kém 5 giờ kém 20 phút là 20 phút

Tìm mẫu số chung

\(\dfrac{2,5}{4}=0,625M\) nha em

a. \(C_{\%_{KCl}}=\dfrac{20}{600}.100\%=3,33\%\)

b. \(2,5kg=2500g\)

\(C_{\%_{Al_2\left(SO_4\right)_3}}=\dfrac{34,2}{2500}.100\%=1,368\%\)

a. Ta có: \(n_{CuSO_4}=\dfrac{400}{160}=2,5\left(mol\right)\)

\(\Rightarrow C_{M_{CuSO_4}}=\dfrac{2,5}{4}=0,625M\)

b. \(V_{dd_{BaCl_2}}=\dfrac{600}{1,2}=500\left(ml\right)=0,5\left(lít\right)\)

\(\Rightarrow C_{M_{BaCl_2}}=\dfrac{0,2}{0,5}=0,4M\)

\(\left(\dfrac{1}{3}+\dfrac{3}{8}-\dfrac{7}{12}\right)\times\dfrac{3}{4}\)

\(=\left(\dfrac{8}{24}+\dfrac{9}{24}-\dfrac{14}{24}\right)\times\dfrac{3}{4}\)

\(=\dfrac{3}{24}\times\dfrac{3}{4}\)

\(=\dfrac{1}{8}\times\dfrac{3}{4}=\dfrac{3}{32}\)

A

\(\dfrac{2}{5}\times\dfrac{3}{7}+\dfrac{2}{5}\times\dfrac{4}{7}+\dfrac{2}{5}\)

C₁:

\(=\dfrac{6}{35}+\dfrac{8}{35}+\dfrac{14}{35}\)

\(=\dfrac{28}{35}=\dfrac{4}{5}\)

C₂:

\(=\dfrac{2}{5}\times\left(\dfrac{3}{7}+\dfrac{4}{7}+1\right)\)

\(=\dfrac{2}{5}\times2\)

\(=\dfrac{4}{5}\)