8.5 Exercise 74

Electronics The resistance of a circuit formed by connecting two resistors in parallel is $\frac{1}{\frac{1}{R_{1}} + \frac{1}{R_{2}}}$.

1. ⓐ Simplify the complex fraction $\frac{1}{\frac{1}{R_{1}} + \frac{1}{R_{2}}}$.
2. ⓑ Find the resistance of the circuit when $R_{1} = 8$ and $R_{2} = 12$.