Can someone tell me how to solve this

Which value is not a solution of 8x^3 – 1 = 0

Which expression is not a polynomial?

What is the expression in factored form? 3x^2 + 18x + 24 a. 3(x+2)(x+4) b. 3(x-2)(x+4) c. 3(x-2)(x-4) d. 3(x+2)(x-4)