Question:

If \( x = \left(\dfrac{3}{2}\right)^{2}\left(\dfrac{2}{3}\right)^{-4} \), the value of \( x^{-2} \) is

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The bases 3/2 and 2/3 are reciprocals. Flip the second one so both factors share the base 3/2, add the exponents to get x, then use the outer power of minus 2.
Updated On: Jul 17, 2026
  • \( \left(\dfrac{2}{3}\right)^{12} \)
  • \( \left(\dfrac{3}{2}\right)^{12} \)
  • \( \left(\dfrac{6}{5}\right)^{-12} \)
  • \( \left(\dfrac{5}{6}\right)^{-12} \)
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The Correct Option is A

Solution and Explanation

Step 1: The rules we need.
A negative exponent flips the base: \( a^{-n} = \dfrac{1}{a^{n}} \), and for a fraction \( \left(\dfrac{p}{q}\right)^{-n} = \left(\dfrac{q}{p}\right)^{n} \).
Same bases multiply by adding exponents: \( a^{m} \cdot a^{n} = a^{m+n} \).
A power raised to a power multiplies exponents: \( (a^{m})^{n} = a^{mn} \).

Step 2: Make both factors share one base.
The two bases \( \frac{3}{2} \) and \( \frac{2}{3} \) are reciprocals, so flip the second one:
\[ \left(\frac{2}{3}\right)^{-4} = \left(\frac{3}{2}\right)^{4} \]
Now \( x \) is a product of two powers of the same base \( \frac{3}{2} \).

Step 3: Simplify x.
\[ x = \left(\frac{3}{2}\right)^{2}\left(\frac{3}{2}\right)^{4} = \left(\frac{3}{2}\right)^{2+4} = \left(\frac{3}{2}\right)^{6} \]

Step 4: Raise to the power minus 2.
\[ x^{-2} = \left[\left(\frac{3}{2}\right)^{6}\right]^{-2} = \left(\frac{3}{2}\right)^{-12} \]
A negative exponent on a fraction flips the fraction:
\[ \left(\frac{3}{2}\right)^{-12} = \left(\frac{2}{3}\right)^{12} \]

Step 5: Numerical check.
\( x = \left(\frac{3}{2}\right)^{6} = \frac{729}{64} \), so \( x^{-2} = \frac{64^{2}}{729^{2}} = \frac{4096}{531441} \).
And \( \left(\frac{2}{3}\right)^{12} = \frac{2^{12}}{3^{12}} = \frac{4096}{531441} \). The two agree.

Step 6: Why the other options are wrong.
Option (B) \( \left(\frac{3}{2}\right)^{12} \) is the reciprocal of the answer. It comes from forgetting to flip the base after the minus sign.
Options (C) and (D) use bases \( \frac{6}{5} \) and \( \frac{5}{6} \), which never appear in the question. Only 2 and 3 are prime factors here, so 5 cannot show up.

Final Answer:
The value of \( x^{-2} \) is option (A). \[ \boxed{\left(\frac{2}{3}\right)^{12}} \]
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