Bounds Expressions 1042Dc
1. **Problem statement:** Given real numbers $x$ and $y$ such that $2 \leq x \leq 5$ and $-3 \leq y \leq 4$, find the bounds (range) for the expressions $x+y$, $x-y$, $xy$, and $y^2$.
2. **Formula and rules:** To find the bounds of sums, differences, products, and powers, use the given intervals and consider the minimum and maximum values by evaluating at the interval endpoints.
3. **Step-by-step solution:**
- For $x+y$:
- Minimum: $2 + (-3) = -1$
- Maximum: $5 + 4 = 9$
- So, $-1 \leq x+y \leq 9$
- For $x-y$:
- Minimum: $2 - 4 = -2$
- Maximum: $5 - (-3) = 8$
- So, $-2 \leq x-y \leq 8$
- For $xy$:
- Since $x$ is positive and $y$ can be negative or positive, check all combinations:
- $2 \times (-3) = -6$
- $2 \times 4 = 8$
- $5 \times (-3) = -15$
- $5 \times 4 = 20$
- Minimum is $-15$, maximum is $20$
- So, $-15 \leq xy \leq 20$
- For $y^2$:
- Since $y$ ranges from $-3$ to $4$, square values range from $0$ to $16$ (because $(-3)^2=9$ and $4^2=16$)
- Minimum is $0$ (at $y=0$), maximum is $16$
- So, $0 \leq y^2 \leq 16$
**Final answer:**
$$
\begin{cases}
-1 \leq x+y \leq 9 \\
-2 \leq x-y \leq 8 \\
-15 \leq xy \leq 20 \\
0 \leq y^2 \leq 16
\end{cases}
$$