Câu 4 là ''Do'' tại aunt có ''s''

1. does

2. does his mom go

3. did they give

4. Does Hoa's aunts go

5. Is he going 

6. did Nam play

7. was cooking / were reading

Khai căn 18 luôn đi ông :)

Bài 1: 

\(pt\Leftrightarrow10x=5\Leftrightarrow x=\dfrac{1}{2}\)

Vậy \(S=\left\{\dfrac{1}{2}\right\}\)

Bài 2:

\(B=x^2+2x-2\) 

Lấy \(x=1\Rightarrow B=1>0\)

Vậy \(B=x^2+2x-2< 0\forall x\in R\) ( vô lí)

\(\%m_{Ca}=\dfrac{40}{164}.100=24,39\left(\%\right)\\ \%m_N=\dfrac{28}{164}.100=17,07\left(\%\right)\\ \%m_O=\dfrac{48.2}{164}.100=58,54\left(\%\right)\)