Question 1000263
Properly stated as plain text,
(6x^4-4x+1) / (4-x)


{{{(6x^4-4x+1) / (4-x)}}}


Start the rational expression this way:
{{{(-1)(6x^4-4x+1) / (x-4)}}}


Account for ALL degrees of x:
{{{(-1)(6x^4+0*x^3+0*x^2-4x+1) / (x-4)}}}


NOW do the synthetic division, and do not forget the factor of {{{-1}}} from the numerator.  (Assumed that was all the help you needed.)