The polynomial function is and upper : x = 4.

The leading coefficient is 1 and the constant term is 1.

Possible rational zeros .

The original polynomial has two variations in signs.

The polynomial has one variations in sign.

From descartes^,s rule of signs, the polynomial has either one negative or no negative real zeros.

By synthetic division, determine that x = 4 is a rational zero.

The x = 4 (4 > 0) is not a zero, since the last row has either  positive or zero entries, we know that x = 4 is an upper bound for the real zeros of f.

The x = 4 is an upper bound for the real zeros of f.