(x + 1 ) is not a factor of the polynomial
given (x - a) is a factor of a polynomial f(x) then x = a is a root and the remainder is f(a) = 0
evaluate the polynomial f(- 1)
f(- 1) = 2(- 1)³ - 9(- 1)² + 17(- 1) - 6
= - 2 - 9 - 17 - 6 = - 34 ≠ 0
Thus (x + 1) is not a factor of the polynomial