College Algebra (10th Edition)

RECALL: If the remainder is zero (or no remainder) when a polynomial is divided by $x-c$, then $x-c$ is a factor of the polynomial. In the given synthetic division, the remainder is zero (as shown in the rightmost entry in the last row). Thus, the binomial $x-(-5) = x+5$ is a factor of the dividend, which is $2x^3+3x^2-38x-15$.