Step 1 :The temperature function is a quadratic function in the form of \(f(x) = ax^2 + bx + c\). The maximum value of a quadratic function is at its vertex. The x-coordinate of the vertex of a quadratic function is given by \(-b/2a\). In this case, \(a = -0.017\) and \(b = 0.4182\). So, we can calculate the time when the patient's temperature reaches its maximum value by using the formula \(-b/2a\).
Step 2 :Substitute \(a = -0.017\) and \(b = 0.4182\) into the formula \(-b/2a\) to get the time when the patient's temperature reaches its maximum value.
Step 3 :The result is approximately 12.3 hours. This means that the patient's temperature reaches its maximum value about 12.3 hours after the illness begins.
Step 4 :Final Answer: The patient's temperature reaches its maximum value after \(\boxed{12.3}\) hours.