In plain text, it is appropriate to express the division using a division bar (/) and parentheses around the numerator and denominator:
(3x^4 +7x^3 +2x^2 +13x +5)/(x^2 +3x +1)
It is best to reserve the square root symbol (√) for an actual square root.
Your quotient is
3x^2 -2x +5