Let's perform the long division
color(white)(aaaa)aaaa2x^2+12x2+1color(white)(aaaa)aaaa|∣6x^3+10x^2+x+86x3+10x2+x+8color(white)(aaaa)aaaa|∣3x+53x+5
color(white)(aaaaaaaaaaaaaaaa)aaaaaaaaaaaaaaaa6x^36x3color(white)(aa aaaaa)aaaaaaa+3x+3xcolor(white)(aaaa)aaaa
color(white)(aaaaaaaaaaaaaaaaa)aaaaaaaaaaaaaaaaa00color(white)(aa aa)aaaa10x^210x2-2x−2xcolor(white)(aaaa)aaaa
color(white)(aaaaaaaaaaaaaaaaa)aaaaaaaaaaaaaaaaacolor(white)(aa aaa)aaaaa10x^210x2color(white)(aaaa)aaaa+5+5color(white)(aaaa)aaaa
color(white)(aaaaaaaaaaaaaaaaa)aaaaaaaaaaaaaaaaacolor(white)(aa aaaa)aaaaaa00color(white)(aaaaaa)aaaaaa+3+3color(white)(aaaa)aaaa
color(white)(aaaaaaaaaaaaaaaaa)aaaaaaaaaaaaaaaaacolor(white)(aa aaaaaa)aaaaaaaa-2x−2xcolor(white)(aa)aa+3+3color(white)(aaaa)aaaa
(6x^3+10x^2+x+8)/(2x^2+1)=(3x+5)+(-2x+3)/(2x^2+1)6x3+10x2+x+82x2+1=(3x+5)+−2x+32x2+1