Answer
See answers.
Work Step by Step
This is discussed in section 21-15. To make the impedance of an LRC circuit a minimum, refer to equation 21-15. Make the resistance R as small as possible. Also, make the reactance of the capacitor equal to that of the inductor, $$X_C=X_L$$.
$$X_L-X_C=0=2\pi f L-\frac{1}{2\pi f C}$$
$$f=\frac{1}{2\pi}\sqrt{\frac{1}{LC}}$$