Question 935082

{{{x^2-4x-7=0}}}...use quadratic formula to find {{{x}}}


{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} ...since {{{a=1}}},{{{b=-4}}}, and {{{c=-7}}} we have

{{{x = (-(-4) +- sqrt( (-4)^2-4*1*(-7) ))/(2*1) }}} 

{{{x = (4 +- sqrt( 16+28 ))/2 }}} 

{{{x = (4 +- sqrt( 44 ))/2 }}}

{{{x = (4 +- sqrt( 4*11 ))/2 }}}

{{{x = (cross(4)2 +- cross(2)*sqrt( 11 ))/cross(2) }}}

{{{x = (2 +- sqrt( 11 )) }}}

exact solutions:

{{{x = 2 + sqrt( 11 ) }}}
{{{x = 2 - sqrt( 11 ) }}}

approximate solutions:

{{{x = 2 + 3.3 =5.3}}}
{{{x = 2 - 3.3=-1.3 }}}

{{{ graph( 600, 600, -10, 10, -10, 10, x^2-4x-7) }}}