Given:
\(\frac{x}{y} < \frac{x+3}{y-3}\)
This inequality can be rewritten as:
\[ \frac{x}{y} - \frac{x+3}{y-3} < 0 \]
Now, let's combine the two fractions:
\[ \Rightarrow \frac{x(y-3) - y(x+3)}{y(y-3)} < 0 \]
Expanding the numerator:
\[ \Rightarrow \frac{xy - 3x - xy - 3y}{y(y - 3)} < 0 \] \[ \Rightarrow \frac{-3(x + y)}{y(y - 3)} < 0 \]
Multiplying both sides by -1 (to make the numerator positive):
\[ \Rightarrow \frac{3(x + y)}{y(y - 3)} > 0 \]
Now, let's analyze the inequality \( \frac{3(x + y)}{y(y - 3)} > 0 \).
For this inequality to be true, we need to consider the conditions for both the numerator and the denominator. We know that:
If \( y < 0 \), then \( y(y - 3) > 0 \) (since the product of two negative numbers is positive). Thus, for the inequality \( \frac{3(x + y)}{y(y - 3)} > 0 \) to hold true, we must have:
\[ x + y > 0 \]
This implies:
\[ x > -y \]
Additionally, since \( x \) and \( y \) are related by their absolute values, we conclude that:
\[ |x| > |y| \]
Therefore, the final conclusion is:
\[ -x < y \]
Conclusion: Therefore, the correct option is (D): "If \( y < 0 \), then \( -x < y \)."
When $10^{100}$ is divided by 7, the remainder is ?