1. **State the problem:** Solve the equation $$\log_2(y^4) + \log_2(y) - \log_2(4y) = 2$$ for $y$.
2. **Recall logarithm properties:**
- $\log_b(a) + \log_b(c) = \log_b(ac)$
- $\log_b(a) - \log_b(c) = \log_b\left(\frac{a}{c}\right)$
- $\log_b(a^n) = n\log_b(a)$
3. **Apply the properties:**
Combine the first two terms:
$$\log_2(y^4) + \log_2(y) = \log_2(y^4 \cdot y) = \log_2(y^5)$$
So the equation becomes:
$$\log_2(y^5) - \log_2(4y) = 2$$
4. **Combine the logarithms:**
$$\log_2\left(\frac{y^5}{4y}\right) = 2$$
Simplify inside the log:
$$\frac{y^5}{4y} = \frac{y^{5-1}}{4} = \frac{y^4}{4}$$
So:
$$\log_2\left(\frac{y^4}{4}\right) = 2$$
5. **Rewrite the logarithmic equation in exponential form:**
$$\frac{y^4}{4} = 2^2$$
$$\frac{y^4}{4} = 4$$
6. **Solve for $y^4$:**
Multiply both sides by 4:
$$\cancel{4} \cdot \frac{y^4}{\cancel{4}} = 4 \cdot 4$$
$$y^4 = 16$$
7. **Solve for $y$:**
Take the fourth root of both sides:
$$y = \pm \sqrt[4]{16}$$
Since $16 = 2^4$,
$$y = \pm 2$$
8. **Check domain restrictions:**
The original logarithms require arguments to be positive:
- $y^4 > 0$ always true for $y \neq 0$
- $y > 0$ so $y$ must be positive
- $4y > 0$ so $y > 0$
Therefore, $y$ must be positive.
9. **Final answer:**
$$\boxed{y = 2}$$
Logarithm Equation Ee5773
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