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The value of (sqrt5+1)^(5)-(sqrt5-1)^(5)...

The value of `(sqrt5+1)^(5)-(sqrt5-1)^(5)` is

A

252

B

352

C

452

D

552

Text Solution

AI Generated Solution

The correct Answer is:
To solve the expression \((\sqrt{5}+1)^{5} - (\sqrt{5}-1)^{5}\), we will use the Binomial Theorem to expand both terms and then simplify. ### Step-by-Step Solution: 1. **Apply the Binomial Theorem**: The Binomial Theorem states that: \[ (x + a)^n = \sum_{k=0}^{n} \binom{n}{k} x^{n-k} a^k \] We will apply this to both \((\sqrt{5}+1)^{5}\) and \((\sqrt{5}-1)^{5}\). 2. **Expand \((\sqrt{5}+1)^{5}\)**: Using the Binomial Theorem: \[ (\sqrt{5}+1)^{5} = \sum_{k=0}^{5} \binom{5}{k} (\sqrt{5})^{5-k} (1)^{k} \] This expands to: \[ = \binom{5}{0} (\sqrt{5})^{5} + \binom{5}{1} (\sqrt{5})^{4} \cdot 1 + \binom{5}{2} (\sqrt{5})^{3} \cdot 1^2 + \binom{5}{3} (\sqrt{5})^{2} \cdot 1^3 + \binom{5}{4} (\sqrt{5})^{1} \cdot 1^4 + \binom{5}{5} (1)^{5} \] Simplifying this gives: \[ = 5\sqrt{5}^5 + 10\sqrt{5}^4 + 10\sqrt{5}^3 + 5\sqrt{5}^2 + 1 \] 3. **Expand \((\sqrt{5}-1)^{5}\)**: Similarly, we expand: \[ (\sqrt{5}-1)^{5} = \sum_{k=0}^{5} \binom{5}{k} (\sqrt{5})^{5-k} (-1)^{k} \] This expands to: \[ = \binom{5}{0} (\sqrt{5})^{5} - \binom{5}{1} (\sqrt{5})^{4} + \binom{5}{2} (\sqrt{5})^{3} - \binom{5}{3} (\sqrt{5})^{2} + \binom{5}{4} (\sqrt{5})^{1} - \binom{5}{5} (1)^{5} \] Simplifying this gives: \[ = 5\sqrt{5}^5 - 10\sqrt{5}^4 + 10\sqrt{5}^3 - 5\sqrt{5}^2 + 1 \] 4. **Combine the Two Expansions**: Now, we subtract the two expansions: \[ (\sqrt{5}+1)^{5} - (\sqrt{5}-1)^{5} = (5\sqrt{5}^5 + 10\sqrt{5}^4 + 10\sqrt{5}^3 + 5\sqrt{5}^2 + 1) - (5\sqrt{5}^5 - 10\sqrt{5}^4 + 10\sqrt{5}^3 - 5\sqrt{5}^2 + 1) \] Simplifying this gives: \[ = 20\sqrt{5}^4 + 10\sqrt{5}^2 \] 5. **Final Simplification**: We can factor out \(10\): \[ = 10(2\sqrt{5}^4 + \sqrt{5}^2) \] Since \(\sqrt{5}^2 = 5\), we have: \[ = 10(2 \cdot 25 + 5) = 10(50 + 5) = 10 \cdot 55 = 550 \] ### Final Answer: The value of \((\sqrt{5}+1)^{5} - (\sqrt{5}-1)^{5}\) is \(550\).
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