[tex]\displaystyle x^2-5x+6=0 \\ a=1,~b=-5,~c=6 \\ \Delta=b^2-4ac=(-5)^2-4 \cdot 1 \cdot 6=25-24=1\ \textgreater \ 0 \\ x_1= \frac{-(-5)- \sqrt{1} }{2 \cdot 1} = \frac{5-1}{2} = \frac{4}{2} =2 \\ x_2= \frac{-(-5)+ \sqrt{1} }{2 \cdot 1} = \frac{5+1}{2} = \frac{6}{2} =3 [/tex]
