[tex]ax^2+bx+c=0\\\\x_1=\dfrac{-b-\sqrt{\Delta}}{2a}\ and\ x_2=\dfrac{-b+\sqrt{\Delta}}{2a}\\\\\Delta=b^2-4ac[/tex]
[tex]y=x^2+5x+c\\\\a=1;\ b=5;\ c=c\\\\x=\dfrac{-5\pm\sqrt\Delta}{2\cdot1}\\\\\Delta=5^2-4\cdot1\cdot c=25-4c\\\\Therefore:x=\dfrac{-5\pm\sqrt{25-4c}}{2}[/tex]
