Question 691845
{{{x^2-4x=1}}}


{{{x^2-4x-1=0}}}


Use the quadratic formula to solve for x


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


{{{x = (-(-4)+-sqrt((-4)^2-4(1)(-1)))/(2(1))}}} Plug in {{{a = 1}}}, {{{b = -4}}}, {{{c = -1}}}


{{{x = (4+-sqrt(16-(-4)))/(2)}}}


{{{x = (4+-sqrt(16+4))/(2)}}}


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


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


{{{x = (4+2*sqrt(5))/2}}} or {{{x = (4-2*sqrt(5))/2}}}


{{{x = 2+sqrt(5)}}} or {{{x = 2-sqrt(5)}}}