Let's do the long division color(white)(aaa)3x^3-5x^2+10x+4color(white)(aaa)∣3x+1 color(white)(aaa)3x^3+x^2color(white)(aaaaaaaaaaaaa)∣x^2-2x+4 color(white)(aaaa)0-6x^2+10x color(white)(aaaaaaa)-6x^2-2x color(white)(aaaaaaaaaa)0+12x+4 color(white)(aaaaaaaaaaaa)+12x+4 color(white)(aaaaaaaaaaaaaa)+0+0