Factorize: $$(y^3 - y)$$

$y ( y - 1 ) ( y + 1 )$
1. We know that \begin{aligned} (a^2 - b^2) = (a + b) (a - b) \end{aligned}
2. Thus \begin{aligned} (y^3 - y) = \space& y( y^2 - 1 ) \\ = \space& y( y^2 - 1^2 ) \\ = \space& y ( y - 1 ) ( y + 1 ) \end{aligned}
3. Thus, $(y^3 - y) = y ( y - 1 ) ( y + 1 )$.