The value of $$ \left(x^{\frac{b+c}{c-a}}\right)^{\frac{1}{a-b}} \cdot \left(x^{\frac{c+a}{a-b}}\right)^{\frac{1}{b-c}} \cdot \left(x^{\frac{a+b}{b-c}}\right)^{\frac{1}{c-a}} $$ is
Aptitude
Surds and Indices
Difficulty: Medium
Choose an option
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A1
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B$a$
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C$b$
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D$c$
Answer
Correct Answer: 1
Explanation
### Concept & Formula
When raising a power to a power, multiply the exponents: $ (x^m)^n = x^{mn} $.
When multiplying terms with the same base, add their exponents: $ x^m \cdot x^n = x^{m+n} $.
For cyclic symmetry problems in competitive exams, the sum of the exponents almost always evaluates to zero.
### Step-by-Step Solution
* **Step 1:** Apply the power-to-a-power rule to simplify each term's exponent.
First term exponent = $ \frac{b+c}{(c-a)(a-b)} $
Second term exponent = $ \frac{c+a}{(a-b)(b-c)} $
Third term exponent = $ \frac{a+b}{(b-c)(c-a)} $
* **Step 2:** Multiply the bases by adding all three exponents together.
Total Exponent = $ \frac{b+c}{(c-a)(a-b)} + \frac{c+a}{(a-b)(b-c)} + \frac{a+b}{(b-c)(c-a)} $
* **Step 3:** Take the Least Common Multiple (LCM) for the denominators, which is $ (a-b)(b-c)(c-a) $.
Adjust the numerators accordingly:
First term numerator = $ (b+c)(b-c) = b^2 - c^2 $
Second term numerator = $ (c+a)(c-a) = c^2 - a^2 $
Third term numerator = $ (a+b)(a-b) = a^2 - b^2 $
* **Step 4:** Sum the numerators.
$ (b^2 - c^2) + (c^2 - a^2) + (a^2 - b^2) = 0 $
* **Step 5:** Evaluate the final base and exponent.
Since the numerator of our exponent is $0$, the total exponent is $0$.
$ x^0 = 1 $ (assuming $x \neq 0$)
### Exam Strategy & Shortcut
**Pattern Recognition:** Cyclic equations (where variables shift in a continuous loop like $a \rightarrow b \rightarrow c$) usually simplify symmetrically. In exponent problems of this exact structure, the exponents invariably cancel out to yield $x^0 = 1$.
**Value Substitution:** If you forget the algebra, assume $a=1, b=2, c=3$. (Never pick values that make a denominator zero). The arithmetic will quickly cancel down to $x^0 = 1$, allowing you to mark the answer in under 15 seconds.
### Common Pitfall
A major trap is making sign errors when establishing the common denominator. For example, treating $(c-a)$ as $-(a-c)$ and losing track of the negative sign will prevent the numerators from perfectly canceling out.
### Final Answer
Therefore, the correct answer is **1**.