The answer is quadratic.
A quadratic equation takes this form:
ax^2+ bx + c
The "a,""b,"and "c" represent numerical coefficients.
This is how your equation looks:
3x + x^2 + 4
Now it is standard that we organize the polynomial in descending order so it will look like this:
x^ 2 + 3x + 4
(commutative property of addition says that the arrangement will not affect the result)
It matches the quadratic polynomial form.
* You might be thinking, x to the second power has no number next to it though, well actually it does. The numerical coefficient of x to the power of two in this case is actually 1. It's just that in math, it is not necessary to put the one anymore. It is already assumed.