\(-\frac{25}{35}\cdot\frac{5}{6}< x< (-2)^2\)

\(\Rightarrow-\frac{25}{7}\cdot\frac{1}{6}< x< 4\)

\(\Rightarrow-\frac{25}{42}< x< 4\)

Tự tìm x nhé :v nếu x không có thì ghi : x không thỏa mãn điều kiện

Đổi : \(40(ml)=0,04(l) , 200(ml)=0,2(l) \)

\(\Rightarrow n_{H_2SO_4} (bđ)=0,04.3=0,12(mol) \)

\(\Rightarrow CM_{H_2SO_4}=\dfrac{0,12}{0,2}=0,6(M)\)

\(33,5.3+33.5.x=335\)

\(33,5.\left(3+x\right)=335\)

\(3+x=10\)

\(x=7\)

x = 7

t mik nha

a) Ta có: \(4\cdot\left(13-16\right)-\left(3-5\right)\cdot\left(-3\right)^2\)

\(=4\cdot13-4\cdot16+2\cdot9\)

\(=52-64+18\)

=6

b) Ta có: \(-\dfrac{2}{5}+\dfrac{7}{11}+\dfrac{-11}{10}+\dfrac{7}{-11}\)

\(=-\left(\dfrac{2}{5}+\dfrac{11}{10}\right)+\left(\dfrac{7}{11}-\dfrac{7}{11}\right)\)

\(=-\left(\dfrac{4}{10}+\dfrac{11}{10}\right)\)

\(=\dfrac{-15}{10}=\dfrac{-3}{2}\)

rồi câu c) d) đâu???

\(PTK_X=102\left(đvC\right)\\ \Rightarrow M_X=102\left(\dfrac{g}{mol}\right)\)

\(\Rightarrow m_O=\%O.M_X=47,06\%.102=48\left(g\right)\)

\(\Rightarrow n_O=\dfrac{m}{M}=\dfrac{48}{16}=3\left(mol\right)\)

\(\Rightarrow CTHH.của.M.có.dạng:X_2O_3\)

\(\Leftrightarrow X.2+16.3=102\\ \Leftrightarrow X=27\left(đvC\right)\)

\(\Rightarrow X.là.Al\left(nhôm\right)\)

\(\Rightarrow CTHH.của.M:Al_2O_3\)

ptk là gì ????/

\(n_{Mg}=\dfrac{m_{Mg}}{M_{Mg}}=\dfrac{4.8}{24}=0,2mol\) 

đổi 200 ml = 0,2 l

PTHH: Mg + 2HCl \(\rightarrow\) MgCl₂ + H₂

TL;        1        2           1          1

mol:     0,2 \(\rightarrow\) 0,2               \(\rightarrow\) 0,2

b. \(C_{M_{ddHCl}}=\dfrac{n_{HCl}}{V_{dd_{HCl}}}=\dfrac{0,2}{0,2}=1M\)  

\(c.V_{H_2}=n_{H_2}.22,4=0,2.22,4=4,48l\) 

\(n_{Mg}=\dfrac{4,8}{24}=0,2\left(mol\right)\)

a) PTHH : \(Mg+2HCl\rightarrow MgCl_2+H_2\)

b) \(n_{HCl}=2n_{Mg}=0,4\left(mol\right)\Rightarrow C_{MddHCl}=\dfrac{0,4}{0,2}=2M\)

c) \(n_{Mg}=n_{H2}=0,2\left(mol\right)\Rightarrow V_{H2\left(dktc\right)}=0,2.22,4=4,48\left(l\right)\)

my school name is dai dong secondary

Name of school( tên trường của bạn) : VD: junior hight Song Da 
Reasons you like it ( lí do bạn thích nó) : VD : Because my school organized a lot of activities appealing.
Reasons you don`t like it ( lí do trường bạn không thích) : VD: Because l have a lot of schools and students are busy taking beautiful car in the garage.

\(\dfrac{3^4.4-6^6}{\text{​3^5.5+10. 3^4}}\)

=\(\dfrac{3^4.2^2-\left(3.2\right)^6}{3^5.5+2.5.3^4}\)

=\(\dfrac{3^4.2^2-3^6.2^6}{3^4.5.\left(3+2\right)}\)

=\(\dfrac{3^4.2^2.\left(1-3^2.2^2\right)}{3^4.5^2}\)

=\(\dfrac{3^4.2^2.\left(-35\right)}{3^4.5^2}\)

=\(\dfrac{2^2.\left(-7\right).5}{5^2}\)

=\(\dfrac{2^2.\left(-7\right)}{5}\)=\(\dfrac{-28}{5}\)