1. **State the problem:** Solve for $ab$ given the equations:
$$(a - 6)(a + 6) = 49$$
$$a^2 + 6^2 = 337$$
$$\sqrt{a} + \sqrt{6} = 7$$
and find the value of $$\frac{ab}{\sqrt{a} - \sqrt{6}}$$.
2. **Use the difference of squares formula:**
$$(a - 6)(a + 6) = a^2 - 6^2 = 49$$
3. **Substitute $6^2 = 36$ and simplify:**
$$a^2 - 36 = 49$$
4. **Add 36 to both sides:**
$$a^2 = 49 + 36 = 85$$
5. **Check the second equation:**
$$a^2 + 6^2 = 337$$
Substitute $6^2 = 36$:
$$a^2 + 36 = 337$$
6. **Subtract 36 from both sides:**
$$a^2 = 337 - 36 = 301$$
7. **Notice the contradiction:**
From step 4, $a^2 = 85$, but from step 6, $a^2 = 301$. This is inconsistent, so we must re-examine the problem.
8. **Re-examine the problem:** The first equation is $(a - 6)(a + 6) = 49$, which simplifies to $a^2 - 36 = 49$, so $a^2 = 85$.
The second equation is $a^2 + 6^2 = 337$, which is $a^2 + 36 = 337$, so $a^2 = 301$.
Since these two values for $a^2$ differ, the problem likely involves different variables or a misinterpretation.
9. **Assuming the second equation is about $a^2 + b^2 = 337$ instead of $a^2 + 6^2$, and $b=6$, then:**
$$a^2 + b^2 = 337$$
$$a^2 + 6^2 = 337$$
$$a^2 + 36 = 337$$
$$a^2 = 301$$
10. **From the first equation, $(a - 6)(a + 6) = 49$, which is $a^2 - 36 = 49$, so:**
$$a^2 = 85$$
This contradicts the previous $a^2 = 301$.
11. **Therefore, the problem likely involves different variables $a$ and $b$ with $b=6$. Let's denote $b=6$ and $a$ unknown. Then:**
From the first equation:
$$(a - b)(a + b) = 49$$
$$a^2 - b^2 = 49$$
From the second equation:
$$a^2 + b^2 = 337$$
12. **Add the two equations:**
$$(a^2 - b^2) + (a^2 + b^2) = 49 + 337$$
$$2a^2 = 386$$
$$a^2 = 193$$
13. **Subtract the first equation from the second:**
$$(a^2 + b^2) - (a^2 - b^2) = 337 - 49$$
$$2b^2 = 288$$
$$b^2 = 144$$
$$b = 12$$
14. **Calculate $a$:**
$$a = \sqrt{193}$$
15. **Given $\sqrt{a} + \sqrt{6} = 7$, solve for $\sqrt{a}$:**
$$\sqrt{a} = 7 - \sqrt{6}$$
16. **Square both sides:**
$$a = (7 - \sqrt{6})^2 = 49 - 2 \times 7 \times \sqrt{6} + 6 = 55 - 14\sqrt{6}$$
17. **Equate this to $a = \sqrt{193}$ from step 14, which is inconsistent, so the problem likely means $\sqrt{a}$ is a number, not $a$ itself. Let's denote $x = \sqrt{a}$, then:**
$$x + \sqrt{6} = 7$$
$$x = 7 - \sqrt{6}$$
18. **Calculate $ab$ using the identity:**
$$(x + y)(x - y) = x^2 - y^2$$
Here, $x = \sqrt{a}$ and $y = \sqrt{6}$.
19. **Calculate $\sqrt{a} - \sqrt{6}$:**
$$\sqrt{a} - \sqrt{6} = x - y = (7 - \sqrt{6}) - \sqrt{6} = 7 - 2\sqrt{6}$$
20. **Calculate $ab$ using:**
$$ab = (\sqrt{a})^2 \times (\sqrt{b})^2 = a \times b$$
Given $b = 6$, and $a = x^2 = (7 - \sqrt{6})^2 = 55 - 14\sqrt{6}$.
So:
$$ab = a \times b = (55 - 14\sqrt{6}) \times 6 = 330 - 84\sqrt{6}$$
21. **Calculate the expression:**
$$\frac{ab}{\sqrt{a} - \sqrt{6}} = \frac{330 - 84\sqrt{6}}{7 - 2\sqrt{6}}$$
22. **Rationalize the denominator:**
Multiply numerator and denominator by the conjugate of the denominator:
$$\frac{330 - 84\sqrt{6}}{7 - 2\sqrt{6}} \times \frac{7 + 2\sqrt{6}}{7 + 2\sqrt{6}} = \frac{(330 - 84\sqrt{6})(7 + 2\sqrt{6})}{7^2 - (2\sqrt{6})^2}$$
23. **Calculate denominator:**
$$49 - 4 \times 6 = 49 - 24 = 25$$
24. **Calculate numerator:**
$$330 \times 7 + 330 \times 2\sqrt{6} - 84\sqrt{6} \times 7 - 84\sqrt{6} \times 2\sqrt{6}$$
$$= 2310 + 660\sqrt{6} - 588\sqrt{6} - 168 \times 6$$
$$= 2310 + (660 - 588)\sqrt{6} - 1008$$
$$= 2310 + 72\sqrt{6} - 1008 = 1302 + 72\sqrt{6}$$
25. **Final expression:**
$$\frac{1302 + 72\sqrt{6}}{25} = \frac{1302}{25} + \frac{72}{25}\sqrt{6}$$
**Answer:**
$$\boxed{\frac{1302}{25} + \frac{72}{25}\sqrt{6}}$$
Solve Ab Expression 62581D
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