Perform a long division
color(white)(aa)aa-x^5+0x^4-4x^3+0x^2+x-12−x5+0x4−4x3+0x2+x−12color(white)(aa)aa|∣x^2-x+3x2−x+3
color(white)(aa)aa-x^5+x^4-3x^3−x5+x4−3x3color(white)(aaaaaaaaaaaaaaaa)aaaaaaaaaaaaaaaa|∣-x^3-x^2-2x+1−x3−x2−2x+1
color(white)(aaaa)aaaa0-1x^4-1x^3+0x^20−1x4−1x3+0x2
color(white)(aaaaaa)aaaaaa-1x^4+1x^3-3x^2−1x4+1x3−3x2
color(white)(aaaaaaaaa)aaaaaaaaa0-2x^3+3x^2+x0−2x3+3x2+x
color(white)(aaaaaaaaaaa)aaaaaaaaaaa-2x^3+2x^2-6x−2x3+2x2−6x
color(white)(aaaaaaaaaaaaaa)aaaaaaaaaaaaaa0+x^2+7x-120+x2+7x−12
color(white)(aaaaaaaaaaaaaaaa)aaaaaaaaaaaaaaaa+x^2-1x+3+x2−1x+3
color(white)(aaaaaaaaaaaaaaaaa)aaaaaaaaaaaaaaaaa-0+8x-15−0+8x−15
Therefore,
(-x^5+0x^4-4x^3+0x^2+x-12)/(x^2-x+3)−x5+0x4−4x3+0x2+x−12x2−x+3
=(-x^3-x^2-2x+1)+(8x-15)/(x^2-x+3)=(−x3−x2−2x+1)+8x−15x2−x+3
The remainder is =(8x-15)=(8x−15) and the quotient is =(-x^3-x^2-2x+1)=(−x3−x2−2x+1)