Trả lời :

Ta có :

 \(\frac{x}{4}=\frac{1}{2}\Rightarrow2x=4\Rightarrow x=2\)

\(\frac{1}{2}=\frac{-y}{3}\Rightarrow2y=-3\Rightarrow y=\frac{-3}{2}\)

\(\frac{x}{4}=\frac{1}{2}=\frac{-y}{3}\)

* \(\frac{x}{4}=\frac{1}{2}\Rightarrow2x=4\Rightarrow x=2\)

* \(\frac{1}{2}=\frac{-y}{3}\Rightarrow3=-2y\Rightarrow y=-\frac{3}{2}\)

Bài làm:

a) Ta có: \(\hept{\begin{cases}4n-1⋮n-1\\n-1⋮n-1\end{cases}\Rightarrow\hept{\begin{cases}4n-1⋮n-1\\4n-4⋮n-1\end{cases}}}\)

\(\Rightarrow4n-1-\left(4n-4\right)⋮n-1\)

\(\Rightarrow3⋮n-1\)

\(\Rightarrow n-1\inƯ\left(3\right)=\left\{-3;-1;1;3\right\}\)

\(\Rightarrow n\in\left\{-2;0;2;4\right\}\)

Vậy \(n\in\left\{-2;0;2;4\right\}\)

b) Ta có: \(\hept{\begin{cases}n-1⋮n^2-2\\n^2-2⋮n^2-2\end{cases}\Rightarrow\hept{\begin{cases}n^2-n⋮n^2-2\\n^2-2⋮n^2-2\end{cases}}}\)

\(\Rightarrow n^2-2-\left(n^2-n\right)⋮n^2-2\)

\(\Rightarrow n-2⋮n^2-2\), mà ta có \(n-1⋮n^2-2\)

\(\Rightarrow n-1-\left(n-2\right)⋮n^2-2\)

\(\Rightarrow1⋮n^2-2\)

\(\Leftrightarrow n^2-2\inƯ\left(1\right)=\left\{-1;1\right\}\)

\(\Leftrightarrow n^2\in\left\{1;3\right\}\)

Mà nếu n² = 3 thì n không là số nguyên

\(\Rightarrow n^2=1\Leftrightarrow\orbr{\begin{cases}n=1\\n=-1\end{cases}}\)

Vậy \(\orbr{\begin{cases}n=1\\n=-1\end{cases}}\)

Học tốt!!!!

1).......to Ho Chi Minh city next week.

2)........to shopping mall last night.

2 câu còn lại hổng biết

1. ___Where is he going to visit next week?

    ___When is he going to visit Ho Chi Minh City?

2. ___Where did they go last night?

    ___When did they go to the shopping mall?

3. ___What is the most expensive house in the town?

4. ___Where did he travelled by plane?