Algebraic Expansion/Examples/(x + 1)^2/Proof 1

Example of Algebraic Expansion

$\paren {x + 1}^2 = x^2 + 2 x + 1$

Proof

Use Square of Sum:

$\forall x, y \in \R: \paren {x + y}^2 = x^2 + 2 x y + y^2$

substituting $1$ for $y$.

$\blacksquare$