Question 629303
You can avoid the fraction this way:
{{{ a = 1/2 }}}
{{{ ( x - a )*( 4x^3 - 2x^2 + 5x - 6 ) }}}
{{{ 4x^4 - 2x^3 + 5x^2 - 6x - 4*a*x^3 + 2*a*x^2 - 5*a*x + 6a }}}
Now collect like terms
{{{ 4x^4 - 2x^3 - 4*a*x^3 + 5x^2 + 2*a*x^2 - 6x - 5*a*x + 6a }}}
{{{ 4x^4 - ( 2 + 4a )*x^3 + ( 5 + 2a )*x^2 - ( 6 + 5a )*x + 6a }}}
Now substitute {{{ a = 1/2 }}}
{{{ 4x^4 - ( 2 + 4*(1/2) )*x^3 + ( 5 + 2*(1/2) )*x^2 - ( 6 + 5*(1/2) )*x + 6*(1/2) }}}
{{{ 4x^4 - 4x^3 + 6x^2 - (17/2)*x + 3 }}}
Hope I got it