The function $f$ is defined as follows. \[ f(x)=\sqrt[3]{x}+3 \] Find $f(-64)$ and $f(8)$

Step 1 ：The function \(f(x)\) is defined as \(f(x)=\sqrt[3]{x}+3\).

Step 2 ：To find \(f(-64)\) and \(f(8)\), we need to substitute \(x\) with \(-64\) and \(8\) respectively in the function and calculate the results.

Step 3 ：Substituting \(x\) with \(-64\) in the function, we get \(f(-64) = \sqrt[3]{-64}+3 = 5+3.464101615137754j\).

Step 4 ：Substituting \(x\) with \(8\) in the function, we get \(f(8) = \sqrt[3]{8}+3 = 5.0\).

Step 5 ：\(\boxed{f(-64) = 5+3.464101615137754j}\) and \(\boxed{f(8) = 5.0}\)