I am trying to align the entries of this vector to the left. Could you help me please? Below is my code and next the result.

```
P=\left(\begin{matrix}
p^{(1)}(x_1,x_2,\cdots,x_{r_1})  \\
\vdots\\
p^{(m_1)}(x_1,x_2,\cdots,x_{r_1}) \\
p^{(m_1+1)}(x_1,x_2,\cdots,x_{r_1}, x_{r_1+1},x_{r_1+2},\cdots,x_{r_2})  \\
\vdots\\
p^{(m_2)}(x_{r_1+1},x{r_1+_2},\cdots,x_{r_1}, x_1,x_2,\cdots,x_{r_2})    \\
\end{matrix}\right)

```

[![enter image description here](https://i.stack.imgur.com/O7yhE.png)](https://i.stack.imgur.com/O7yhE.png)