Let's start with the terms: #color(blue)("dividend")# and #color(red)("divisor")#
In the expression: #color(blue)(x^3-3x^2+7x-1) div color(red)(x-3)#
#color(blue)(x^3-3x^2+7x-1)# is the #color(blue)("dividend")#
and
#color(red)(x-3)# is the #color(red)("divisor")#
Performing synthetic division:
#{:
(color(white)("xxx"),,color(gray)(x^3),color(gray)(x^2),color(gray)(x^1),color(gray)(x^0)),
(," | ",1,-3,7,-1),
(ul(+color(white)("X")),ul(" | "),ul(color(white)("xxx")),ul(3),ul(0),ul(21)),
(xx3," | ",color(lime)1,color(lime)0,color(lime)7,color(magenta)20),
(,,color(gray)(x^2),color(gray)(x^1),color(gray)(x^0),color(gray)("Remainder"))
:}#
#color(lime)1#, #color(lime)0#, and #color(lime)7# are the coefficients of the #color(lime)("quotient")#
and
#color(magenta)(20)# is the #color(magenta)("Remainder")#
Therefore in the form
#color(white)("XXX")color(blue)("dividend")=color(lime)("quotient") * color(red)("divisor") + color(magenta)("remainder")#
we have
#color(white)("XXX")color(blue)(""(x^3-3x^2+7x-1))=color(lime)(""(1x^2+0x+7)) * color(red)(""(x-3))+color(magenta)(20)#