Answer
$y^{2} -\frac{1}{y^{2}}$
Work Step by Step
$(y -\frac{1}{y})(y +\frac{1}{y})$
1. Square the first term. $(y)^{2} = y^{2}$
2. Multiply the last terms inside each bracket together. $(-\frac{1}{y})(\frac{1}{y}) = \frac{-1}{y^{2}}$
3. Add your answers from steps 1-2 to get $y^{2} -\frac{1}{y^{2}}$.
