Limit Delta De9Ebd
1. **State the problem:**
Given $\epsilon = 2023$, find $\delta > 0$ such that for all $(x,y)$, we have
$$|f(x,y) - f(0,0)| < \epsilon$$
whenever
$$x^2 + y^2 < \delta,$$
where
$$f(x,y) = \frac{y}{x^2 + 1}.$$
2. **Evaluate $f(0,0)$:**
$$f(0,0) = \frac{0}{0^2 + 1} = 0.$$
3. **Rewrite the inequality:**
We want
$$\left| \frac{y}{x^2 + 1} - 0 \right| = \left| \frac{y}{x^2 + 1} \right| < 2023$$
whenever
$$x^2 + y^2 < \delta.$$
4. **Analyze the function:**
Note that for all real $x$,
$$x^2 + 1 \geq 1,$$
so
$$\left| \frac{y}{x^2 + 1} \right| \leq |y|.$$
5. **Use the condition on $(x,y)$:**
Since
$$x^2 + y^2 < \delta,$$
we have
$$|y| \leq \sqrt{x^2 + y^2} < \sqrt{\delta}.$$
6. **Combine inequalities:**
Therefore,
$$\left| \frac{y}{x^2 + 1} \right| < \sqrt{\delta}.$$
7. **Find $\delta$ to satisfy the inequality:**
We want
$$\sqrt{\delta} < 2023,$$
which implies
$$\delta < 2023^2 = 4092529.$$
8. **Conclusion:**
Any
$$\delta > 0$$
such that
$$\delta < 4092529$$
will satisfy the condition
$$|f(x,y) - f(0,0)| < 2023$$
whenever
$$x^2 + y^2 < \delta.$$