The impedance for a RLC circuit is
Z=R2+(XL−XC)2Z = \sqrt{R^{2} + (X_{L} - X_{C})^{2}}Z=R2+(XL−XC)2
= 102+(9−4)2\sqrt{10^{2} + (9 - 4)^{2}}102+(9−4)2
= 125\sqrt{125}125
= 11.18Ω\OmegaΩ ≈eq\approx\mathrm{eq}≈eq 11.2Ω\OmegaΩ
