Question 980293
{{{3x^3-5x^2-8x-2=0}}}...............factor, write {{{-5x^2}}} as {{{x^2-6x^2}}} and {{{-8x}}} as {{{-2x-6x}}}
{{{3x^3+x^2-6x^2-2x-6x-2=0}}}.....group
{{{(3x^3+x^2)-(6x^2+2x)-(6x+2)=0}}}
{{{x^2(3x+1)-2x(3x+1)-2(3x+1)=0}}}
{{{(3x+1) (x^2-2x-2)=0}}}

zeros:
{{{(3x+1) =0}}}=>{{{highlight(x=-1/3)}}}

{{{ (x^2-2x-2)=0}}}....use quadratic formula

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

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

{{{x = (2 +- sqrt( 4+8 ))/2 }}}

{{{x = (2 +- sqrt( 12 ))/2 }}}

{{{x = (2 +- sqrt( 4*3 ))/2 }}}

{{{x = (cross(2)1 +- cross(2)sqrt( 3 ))/cross(2) }}}

{{{x = (1 +- sqrt( 3 )) }}}

so, other two zeros are: {{{highlight(x = 1 + sqrt( 3 )) }}} and {{{highlight(x = 1 - sqrt( 3 )) }}}