În cazul general avem:[tex]ax^2+bx+c = 0\\~
\Delta = b^2-4ac\\~ x_1 = \frac{-b+\sqrt{\Delta}}{2a}\\~
x_2 = \frac{-b-\sqrt{\Delta}}{2a}[/tex]
[tex]x^2-8x+15 = 0\\~
\Delta = (-8)^2-4*1*15 = 64 - 60 = 4\\~
x_1 = \frac{-(-8)+\sqrt{4}}{2*(1)} = \frac{8+2}{2}=5\\~
x_2 = \frac{8-2}{2}=3[/tex]
