Phương pháp giải

Cho hai mặt phẳng: \(\left\{ \begin{align}  & \left( \alpha  \right):\ \ {{a}_{1}}x+{{b}_{1}}y+{{c}_{1}}z+{{d}_{1}}=0 \\  & \left( \beta  \right):\ \ {{a}_{2}}x+{{b}_{2}}y+{{c}_{2}}z+{{d}_{2}}=0\  \\ \end{align} \right..\)  Khi đó \(\left( \alpha  \right)//\left( \beta  \right)\Leftrightarrow \frac{{{a}_{1}}}{{{a}_{2}}}=\frac{{{b}_{1}}}{{{b}_{2}}}=\frac{{{c}_{1}}}{{{c}_{2}}} e \frac{{{d}_{1}}}{{{d}_{2}}}.\)