Answer :
[tex] a(a-3) =100\\
a^2-3a-100=0\\
\Delta=(-3)^2-4\cdot1\cdot(-100)=9+400=409\\
\sqrt{\Delta}=\sqr{409}\\
a_1=\dfrac{-(-3)-\sqrt{409}}{2\cdot1}=\dfrac{3-\sqrt{409}}{2}\\
a_2=\dfrac{-(-3)+\sqrt{409}}{2\cdot1}=\dfrac{3+\sqrt{409}}{2}[/tex]
