Đáp án + Giải thích các bước giải:

 Lập bảng:

\begin{array}{|c|c|c|}\hline \text{x}&\text{0}&\text{-2/3}\\\hline \text{y=3x+2}&\text{2}&\text{0}\\\hline\end{array} 

\begin{array}{|c|c|c|}\hline \text{x}&\text{0}&\text{3}\\\hline \text{y=x-3}&\text{-3}&\text{0}\\\hline\end{array} 

\begin{array}{|c|c|c|}\hline \text{x}&\text{0}&\text{1}\\\hline \text{y=1/2-x}&\text{1/2}&\text{-1/2}\\\hline\end{array}