[tex] x^{2} -18x+58=0[/tex]
We have got quadratic equation. We calculate it by using Δ.
[tex]\Delta=(-18)^{2} -4*1*58=324-232=92>0[/tex]
[tex] \sqrt{\Delta} = \sqrt{92} =2 \sqrt{23} [/tex]
[tex]x_1= \frac{-b- \sqrt{\Delta} }{2a} = \frac{18-2 \sqrt{23} }{2} =9- \sqrt{23} [/tex]
∨
[tex]x_2= \frac{-b+ \sqrt{\Delta} }{2a} = \frac{18+2 \sqrt{23} }{2} =9+ \sqrt{23} [/tex]
Hope it helps :)
