1. **Problem:** Solve the equation $$\sqrt[4]{0.04^x} = 125^{x-2}$$.
2. **Formula and rules:**
- Recall that $$\sqrt[4]{a} = a^{\frac{1}{4}}$$.
- Express numbers as powers of primes for easier comparison.
3. **Rewrite the equation:**
$$\sqrt[4]{0.04^x} = (0.04^x)^{\frac{1}{4}} = 0.04^{\frac{x}{4}}$$
4. **Express 0.04 and 125 as powers:**
- $$0.04 = \frac{4}{100} = \frac{2^2}{10^2} = \frac{2^2}{(2 \cdot 5)^2} = \frac{2^2}{2^2 \cdot 5^2} = 5^{-2}$$
- So, $$0.04 = 5^{-2}$$
- $$125 = 5^3$$
5. **Rewrite the equation with powers of 5:**
$$0.04^{\frac{x}{4}} = 125^{x-2} \implies (5^{-2})^{\frac{x}{4}} = (5^3)^{x-2}$$
6. **Simplify exponents:**
$$5^{-\frac{2x}{4}} = 5^{3(x-2)} \implies 5^{-\frac{x}{2}} = 5^{3x - 6}$$
7. **Set exponents equal:**
$$-\frac{x}{2} = 3x - 6$$
8. **Solve for $$x$$:**
Multiply both sides by 2:
$$-x = 6x - 12$$
Add $$x$$ to both sides:
$$0 = 7x - 12$$
Add 12 to both sides:
$$12 = 7x$$
Divide both sides by 7:
$$x = \frac{12}{7}$$
**Final answer:** $$x = \frac{12}{7}$$ (Option D)
Fourth Root Equation 49Edd8
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