For what value of a is p(x) - 4x3 + ax2 - x -1 exactly divisible by g(x)=2x + 1?

and g(x)=2x+1

By the factor theorem,p(x) will be exactly divisible by

For what value of a is p(x) - 4x3 + ax2 - x -1 exactly divisible by g(x)=2x + 1?

and g(x)=2x+1

By the factor theorem,p(x) will be exactly divisible by