Select the factored form of this expression \[ 5 y^{2}-25 \]

To factor the expression \( 5y^{2} - 25 \), we can start by noticing that both terms have a common factor of 5. So, we can factor out the 5: \[ 5(y^{2} - 5). \] Now, we check if \( y^{2} - 5 \) can be factored further. Since it's a difference of squares, we can rewrite it as: \[ 5(y - \sqrt{5})(y + \sqrt{5}). \] Therefore, the complete factored form of the expression \( 5y^{2} - 25 \) is: \[ 5(y - \sqrt{5})(y + \sqrt{5}). \] You just unveiled a little treasure of math!