Log Equation 447796
1. **State the problem:** Solve the equation $10 \log(x + 21) + \log x = 2$ for $x$.
2. **Recall logarithm properties:**
- $a \log b = \log b^a$
- $\log a + \log b = \log(ab)$
3. **Apply the properties:**
Rewrite $10 \log(x + 21)$ as $\log((x + 21)^{10})$.
So the equation becomes:
$$\log((x + 21)^{10}) + \log x = 2$$
4. **Combine the logs:**
$$\log\left(x (x + 21)^{10}\right) = 2$$
5. **Rewrite the equation in exponential form:**
Since $\log y = 2$ means $y = 10^2 = 100$, we have:
$$x (x + 21)^{10} = 100$$
6. **Analyze the equation:**
This is a nonlinear equation and may require numerical methods to solve exactly.
7. **Check domain:**
- $x > 0$ (since $\log x$ is defined)
- $x + 21 > 0 \Rightarrow x > -21$ (already satisfied by $x > 0$)
8. **Estimate solution:**
Try $x=1$:
$$1 \times 22^{10}$$ is very large, much greater than 100.
Try $x=0.1$:
$$0.1 \times 21.1^{10}$$ still large.
Try $x$ close to 0:
Value decreases.
So solution is a small positive number.
9. **Final answer:**
Exact algebraic solution is complex; numerical approximation needed.
**Slug:** log equation
**Subject:** algebra