1. **Problem a:** Two numbers have a sum of 29 and we want to find the two numbers that maximize their product.
2. Let the two numbers be $x$ and $y$. We know:
$$x + y = 29$$
3. Express $y$ in terms of $x$:
$$y = 29 - x$$
4. The product $P$ is:
$$P = x \times y = x(29 - x) = 29x - x^2$$
5. This is a quadratic function:
$$P(x) = -x^2 + 29x$$
6. The graph of $P(x)$ is a parabola opening downward (since the coefficient of $x^2$ is negative), so it has a maximum at its vertex.
7. The vertex $x$-coordinate is given by:
$$x = -\frac{b}{2a} = -\frac{29}{2 \times (-1)} = \frac{29}{2} = 14.5$$
8. Find $y$:
$$y = 29 - 14.5 = 14.5$$
9. Calculate the maximum product:
$$P_{max} = 14.5 \times 14.5 = 210.25$$
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10. **Problem b:** Two numbers have a difference of 13 and we want to find the two numbers that minimize their product.
11. Let the two numbers be $x$ and $y$ such that:
$$x - y = 13$$
12. Express $y$ in terms of $x$:
$$y = x - 13$$
13. The product $P$ is:
$$P = x \times y = x(x - 13) = x^2 - 13x$$
14. This is a quadratic function:
$$P(x) = x^2 - 13x$$
15. The graph of $P(x)$ is a parabola opening upward (since the coefficient of $x^2$ is positive), so it has a minimum at its vertex.
16. The vertex $x$-coordinate is:
$$x = -\frac{b}{2a} = -\frac{-13}{2 \times 1} = \frac{13}{2} = 6.5$$
17. Find $y$:
$$y = 6.5 - 13 = -6.5$$
18. Calculate the minimum product:
$$P_{min} = 6.5 \times (-6.5) = -42.25$$
**Final answers:**
- a) The two numbers are 14.5 and 14.5 with maximum product 210.25.
- b) The two numbers are 6.5 and -6.5 with minimum product -42.25.
Quadratic Products Cb9746
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