Given \(f(x) = 3x + 2\), we are often asked to find \(f(2)\) or \(f( - 3)\). To do this we substitute \(2\) or \(- 3\) for \(x\). So, \(f(2) = 3(2) + 2 = 8\) and \(f( - 3) = 3( - 3) + 2 = - 7\).
Sometimes, however, we are asked to find the result of a function of a function. That is, replacing \(x\) in the example above with another function.
