Question 640533
{{{x = (-b+-sqrt(b^2-4ac))/(2a)}}}


{{{x = (-(-1)+-sqrt((-1)^2-4(1)(-20)))/(2(1))}}}


{{{x = (1+-sqrt(1-(-80)))/(2)}}}


{{{x = (1+-sqrt(1+80))/(2)}}}


{{{x = (1+-sqrt(81))/2}}}


{{{x = (1+sqrt(81))/2}}} or {{{x = (1-sqrt(81))/2}}}


{{{x = (1+9)/2}}} or {{{x = (1-9)/2}}}


{{{x = 10/2}}} or {{{x = -8/2}}}


{{{x = 5}}}    or    {{{x = -4}}}