Expression Relations
1. **State the problem:** Given the system of equations:
$$a^7 + b^7 = n$$
$$a^3 + b^3 = p^3$$
$$m^3 + 2p^3 = 3mn$$
$$a + b = m$$
We want to analyze relationships between these variables.
2. **Express powers in terms of $a$ and $b$:**
We know:
$$a + b = m$$
$$a^3 + b^3 = p^3$$
$$a^7 + b^7 = n$$
Recall sum of cubes identity:
$$a^3 + b^3 = (a+b)(a^2 - ab + b^2)$$
So,
$$p^3 = m (a^2 - ab + b^2)$$
3. **Express $a^2 - ab + b^2$ in terms of $m$ and $ab$:**
Since,
$$a^2 + b^2 = (a+b)^2 - 2ab = m^2 - 2ab$$
Therefore,
$$a^2 - ab + b^2 = a^2 + b^2 - ab = m^2 - 3ab$$
Substituting into $p^3$:
$$p^3 = m (m^2 - 3ab) = m^3 - 3m ab$$
So,
$$p^3 = m^3 - 3m ab$$
4. **Rewrite the third equation $m^3 + 2p^3 = 3mn$ using $n = a^7 + b^7$:
$$m^3 + 2p^3 = 3m n$$
Substitute $p^3$ in:
$$m^3 + 2(m^3 - 3m ab) = 3m n$$
Simplify left side:
$$m^3 + 2m^3 - 6 m ab = 3m n$$
$$3m^3 - 6 m ab = 3m n$$
Divide both sides by $3m$ (assuming $m
eq 0$):
$$m^2 - 2 ab = n$$
5. **Final relation:**
Therefore,
$$n = m^2 - 2 ab$$
Given $m = a + b$ and $ab$ is symmetric product, this expresses $n$ in terms of $m$ and $ab$.
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**Summary:**
- From the given system, we derived:
$$p^3 = m^3 - 3 m ab$$
$$n = m^2 - 2 ab$$
These identities relate the variables $a,b,m,n,p$ under the given constraints.
**Note:** Without additional information on $ab$, we cannot solve numerically but have established key polynomial relations.