Chapter 3 - Polynomial and Rational Functions - Section 3.2 The Real Zeros of a Polynomial Function - 3.2 Assess Your Understanding - Page 225: 113

$5$.

Step 1. Use synthetic division as shown in the figure to get the quotient. Step 2. Find other zeros $x^2-5x+1=0 \Longrightarrow x=\frac{5\pm\sqrt {25-4}}{2}=\frac{5\pm\sqrt {21}}{2}$ Step 3. Thus the sum of the remaining solutions is $5$.