Polynomial conditions.
a) If the degree is even and the leading coefficient is positive, the polynomial rises on the left and rises on the right.
b) If the degree is even and the leading coefficient is negative, the polynomial falls on the left and falls on the right.
c) If the degree is odd and the leading coefficient is positive, the polynomial falls on the left and rises on the right.
d) If the degree is odd and the leading coefficient is negative, the polynomial rises on the left and fall on the right.