show that 2x + 1 is a factor of p(x) = 2x³ - 11x² - 4x+ 1

2x+1=0
x = -1/2
2(-1/8) - 11(1/4)-4(-1/2)+1
-1/4 - 11/4 + 2 + 1. 
-12/4 + 3
-3+3
=0
So, (2x+1) is a factor of 2x^​3 - 11x² - 4x + 1