Barycentric coordinates/Point representation/Exercise

Let ${\displaystyle {}P}$ be a point in an affine space ${\displaystyle {}E}$ over ${\displaystyle {}V}$. Show that the following expressions are barycentric combinations for ${\displaystyle {}P}$ (let ${\displaystyle {}Q\in E}$ and ${\displaystyle {}v\in V}$).

1. ${\displaystyle {}P}$.
2. ${\displaystyle {}P+Q-Q}$.
3. ${\displaystyle {}(P+v)-(Q+v)+Q}$.