If -1 is a zero of polynomial p (x) ax³ - x² + x +4 find the value of a

The given polynomial is $p\left(x\right) = a{x}^3-x^2+x+4$
Since -1 is a zero of the given polynomial, so we have;
$$\begin{gathered} p\left(-1\right) = a{\left(-1\right)}^3-{\left(-1\right)}^2+\left(-1\right)+4 = 0 \\ \Rightarrow -a-1-1+4 = 0 \\ \Rightarrow -a+2 = 0 \\ \Rightarrow a = 2 \end{gathered}$$
Therefore the value of a is 2.