1. The problem asks whether the bar (fraction line) in the expression $$\left( \frac{z_1}{z_2} \right) = \frac{a_1 + b_1 i}{a_2 + b_2 i}$$ only affects the numerator. 2. In a fraction, the bar separates the numerator and the denominator. Here, the entire numerator is $z_1$ and the entire denominator is $z_2$. 3. The expression on the right side shows $z_1 = a_1 + b_1 i$ and $z_2 = a_2 + b_2 i$, so the bar affects both the numerator and denominator as a whole. 4. Therefore, the bar affects the entire numerator and the entire denominator, not just the numerator. Final answer: The bar affects both numerator and denominator, not only the numerator.