Equation of Plane

Theorem
A plane $$P$$ is the set of all $$\left({x_1, x_2, x_3}\right) \in \mathbb{R}^3$$, where $$\alpha_1 x_1 + \alpha_2 x_2 + \alpha_3 x_3 = \gamma$$,

where $$\alpha_1, \alpha_2, \alpha_3, \gamma \in \mathbb{R}$$ are given, and not all of $$\alpha_1, \alpha_2, \alpha_3$$ are zero.