If `veca,vecb,vecc` are coplanar vectors then find value of `[veca-vecb+vec2c vecb-vec c+2veca veca+2vecb-vec c]`

Explanation

To solve the problem, we need to find the value of the scalar triple product of the vectors \(\vec{a} - \vec{b} + 2\vec{c}\), \(\vec{b} - \vec{c} + 2\vec{a}\), and \(\vec{a} + 2\vec{b} - \vec{c}\).

### Step-by-Step Solution:

1. **Identify the Vectors**:
Let:
\[
\vec{u} = \vec{a} - \vec{b} + 2\vec{c}
...