Estimating roots The values of various roots can be approximated using Newton's method. For example, to approximate the value of $\sqrt[3]{10},$ we let $x=\sqrt[3]{10}$ and cube both sides of the equation to obtain $x^{3}=10,$ or $x^{3}-10=0 .$ Therefore, $\sqrt[3]{10}$ is a root of $p(x)=x^{3}-10,$ which we can approximate by applying Newton's method. Approximate each value of $r$ by first finding a polynomial with integer coefficients that has a root $r$. Use an appropriate value of $x_{0}$ and stop calculating approximations when two successive approximations agree to five digits to the right of the decimal point after rounding.
$$r=2^{1 / 3}$$