Answer :

To solve the equation [tex]\(\left(\frac{729}{8x}\right)^{\frac{1}{3}} = \frac{9}{4}\)[/tex], follow these steps:

1. Isolate the fractional exponent:
[tex]\[ \left(\frac{729}{8x}\right)^{\frac{1}{3}} = \frac{9}{4} \][/tex]

2. Eliminate the cube root by cubing both sides of the equation:
[tex]\[ \left[\left(\frac{729}{8x}\right)^{\frac{1}{3}}\right]^3 = \left(\frac{9}{4}\right)^3 \][/tex]
Simplifying the left side:
[tex]\[ \frac{729}{8x} = \left(\frac{9}{4}\right)^3 \][/tex]

3. Calculate [tex]\(\left(\frac{9}{4}\right)^3\)[/tex]:
[tex]\[ \left(\frac{9}{4}\right)^3 = \frac{9^3}{4^3} = \frac{729}{64} \][/tex]

4. Set up the equation with the simplified right-hand side expression:
[tex]\[ \frac{729}{8x} = \frac{729}{64} \][/tex]

5. To solve for [tex]\(x\)[/tex], equate the two fractions:
[tex]\[ \frac{729}{8x} = \frac{729}{64} \][/tex]

6. Cross-multiply to solve for [tex]\(x\)[/tex]:
[tex]\[ 729 \cdot 64 = 729 \cdot 8x \][/tex]

7. Simplify the equation:
Divide both sides by 729:
[tex]\[ 64 = 8x \][/tex]

8. Isolate [tex]\(x\)[/tex] by dividing both sides by 8:
[tex]\[ x = \frac{64}{8} \][/tex]

9. Simplify the division:
[tex]\[ x = 8 \][/tex]

Thus, the value of [tex]\(x\)[/tex] is [tex]\(\boxed{8}\)[/tex].