by comparing with equation
[tex]a x^{2} +bx+c=0[/tex]
for equation
[tex] x^{2} -10x+18=0,a=1,b=-10,c=18[/tex]
sub. a,b and c in the formula
[tex]x= \frac{-b+ \sqrt{ b^{2}-4ac } }{2a}, \frac{-b- \sqrt{ b^{2}-4ac } }{2a} [/tex]
u can find that roots are [tex]5- \sqrt{7},5+ \sqrt{7} [/tex]
