1. **State the problem:** We need to divide 24 into three parts $x$, $y$, and $z$ such that $x + y + z = 24$ and the product $P = x \cdot y^2 \cdot z^3$ is maximized.
2. **Express the problem mathematically:**
We want to maximize
$$P = x y^2 z^3$$
subject to
$$x + y + z = 24.$$
3. **Use the constraint to express one variable in terms of the others:**
$$x = 24 - y - z.$$
4. **Rewrite the product in terms of $y$ and $z$ only:**
$$P = (24 - y - z) y^2 z^3.$$
5. **Set up the problem for optimization:**
We want to find $y$ and $z$ that maximize
$$P(y,z) = (24 - y - z) y^2 z^3,$$
with $y > 0$, $z > 0$, and $x = 24 - y - z > 0$.
6. **Use logarithms to simplify differentiation:**
Let
$$\ln P = \ln(24 - y - z) + 2 \ln y + 3 \ln z.$$
7. **Find partial derivatives and set them to zero:**
$$\frac{\partial \ln P}{\partial y} = -\frac{1}{24 - y - z} + \frac{2}{y} = 0,$$
$$\frac{\partial \ln P}{\partial z} = -\frac{1}{24 - y - z} + \frac{3}{z} = 0.$$
8. **From the first equation:**
$$-\frac{1}{24 - y - z} + \frac{2}{y} = 0 \implies \frac{1}{24 - y - z} = \frac{2}{y} \implies y = 2(24 - y - z).$$
9. **From the second equation:**
$$-\frac{1}{24 - y - z} + \frac{3}{z} = 0 \implies \frac{1}{24 - y - z} = \frac{3}{z} \implies z = 3(24 - y - z).$$
10. **Rewrite the two equations:**
$$y = 48 - 2y - 2z \implies 3y + 2z = 48,$$
$$z = 72 - 3y - 3z \implies 3y + 4z = 72.$$
11. **Solve the system:**
Subtract the first from the second:
$$(3y + 4z) - (3y + 2z) = 72 - 48 \implies 2z = 24 \implies z = 12.$$
12. **Find $y$:**
From $3y + 2z = 48$,
$$3y + 2(12) = 48 \implies 3y + 24 = 48 \implies 3y = 24 \implies y = 8.$$
13. **Find $x$:**
$$x = 24 - y - z = 24 - 8 - 12 = 4.$$
14. **Check positivity:** All parts $x=4$, $y=8$, $z=12$ are positive.
15. **Calculate maximum product:**
$$P = 4 \times 8^2 \times 12^3 = 4 \times 64 \times 1728 = 442,368.$$
**Final answer:** The three parts are $4$, $8$, and $12$ and the maximum product is $442,368$.
Max Product Parts
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