The above proposition shows that a straight line is a solution set of a linear equation with two unknowns. In other words, given a point A=(\alpha_1,\alpha_2) in a number plane \mathbb R^2 which is not the origin and a number b\in\mathbb R, a straight line L is a subset of all points of the plane \mathbb R^2 defined as
L:=\{P\in\mathbb R^2:\; P=(x_1,x_2): \alpha_1x_1+\alpha_2x_2=\beta\}.
This concept can be generalized.
For n\ge 1, given a point A\in\mathbb R^n in the number space \mathbb R^n which is not the origin, as well as a number b\in\mathbb R, a hyperplane H is the set of solutions of the linear equation with n unknowns:
H:=\{P\in\mathbb R^n:\; P=(x_1,\dots,x_n): \alpha_1x_1+\ldots+\alpha_nx_n=\beta\}.
Explanations: 1