y^2 = \frac{81}{4}=> y1 = \sqrt{ \frac{9}{2} }= \sqrt{4,5 } , x2= -\sqrt{ \frac{9}{2} }=- \sqrt{4,5} " alt="4y^2 = 81 => y^2 = \frac{81}{4}=> y1 = \sqrt{ \frac{9}{2} }= \sqrt{4,5 } , x2= -\sqrt{ \frac{9}{2} }=- \sqrt{4,5} " align="absmiddle" class="latex-formula">