0\\ \Delta=a^2-4\cdot1\cdot5\\ \Delta=a^2-20\\ a^2-20>0\\ a^2>20\\ a>\sqrt{20} \vee a<-\sqrt{20}\\ a>2\sqrt{5} \vee a<-2\sqrt{5}\\ a\in(-\infty,-2\sqrt{5})\cup(2\sqrt{5},\infty)" alt="\\\Delta>0\\ \Delta=a^2-4\cdot1\cdot5\\ \Delta=a^2-20\\ a^2-20>0\\ a^2>20\\ a>\sqrt{20} \vee a<-\sqrt{20}\\ a>2\sqrt{5} \vee a<-2\sqrt{5}\\ a\in(-\infty,-2\sqrt{5})\cup(2\sqrt{5},\infty)" align="absmiddle" class="latex-formula">