Let's perform the synthetic division
color(white)(aaaa)aaaa-3−3color(white)(aaaaaa)aaaaaa|∣color(white)(aa)aa11color(white)(aaaa)aaaa-2−2color(white)(aaaaaa)aaaaaa44color(white)(aaaaaaa)aaaaaaa66
color(white)(aaaaaaaaaaaa)aaaaaaaaaaaa_________
color(white)(aaaa)aaaacolor(white)(aaaaaaa)aaaaaaa|∣color(white)(aaaa)aaaacolor(white)(aaaaa)aaaaa-3−3color(white)(aaAaa)aaAaa1515color(white)(aaaaa)aaaaa-57−57
color(white)(aaaaaaaaaaaa)aaaaaaaaaaaa________
color(white)(aaaa)aaaacolor(white)(aaaaaaa)aaaaaaa|∣color(white)(aaa)aaa11color(white)(aaaaa)aaaaa-5−5color(white)(aaaaaa)aaaaaa1919color(white)(aaaa)aaaacolor(red)(-51)−51
The remainder is color(red)(-51)−51 and the quotient is =x^2-5x+19=x2−5x+19
Therefore,
(x^3-2x^2+4x+6)/(x+3)=x^2-5x+19-51/(x+3)x3−2x2+4x+6x+3=x2−5x+19−51x+3