1. **State the problem:** Solve the equation $2^x = 7 + 2^{2-x}$ for $x$.
2. **Rewrite the equation:** The equation is $2^x = 7 + 2^{2-x}$.
3. **Express $2^{2-x}$ in terms of $2^x$: **
Recall that $2^{2-x} = 2^2 \cdot 2^{-x} = 4 \cdot \frac{1}{2^x} = \frac{4}{2^x}$.
4. **Substitute into the equation:**
$$2^x = 7 + \frac{4}{2^x}$$
5. **Multiply both sides by $2^x$ to clear the denominator:**
$$\cancel{2^x} \cdot 2^x = 7 \cdot \cancel{2^x} + 4$$
$$ (2^x)^2 = 7 \cdot 2^x + 4$$
6. **Let $y = 2^x$, then the equation becomes:**
$$y^2 = 7y + 4$$
7. **Rewrite as a quadratic equation:**
$$y^2 - 7y - 4 = 0$$
8. **Use the quadratic formula to solve for $y$:**
$$y = \frac{7 \pm \sqrt{(-7)^2 - 4 \cdot 1 \cdot (-4)}}{2 \cdot 1} = \frac{7 \pm \sqrt{49 + 16}}{2} = \frac{7 \pm \sqrt{65}}{2}$$
9. **Calculate the approximate values:**
$$\sqrt{65} \approx 8.062$$
So,
$$y_1 = \frac{7 + 8.062}{2} = \frac{15.062}{2} = 7.531$$
$$y_2 = \frac{7 - 8.062}{2} = \frac{-1.062}{2} = -0.531$$
10. **Since $y = 2^x$ and $2^x > 0$ for all real $x$, discard $y_2 = -0.531$ (negative).**
11. **Solve for $x$ using $y_1 = 7.531$:**
$$2^x = 7.531$$
Take logarithm base 2 on both sides:
$$x = \log_2(7.531) = \frac{\ln(7.531)}{\ln(2)}$$
12. **Calculate the value:**
$$\ln(7.531) \approx 2.020$$
$$\ln(2) \approx 0.693$$
$$x \approx \frac{2.020}{0.693} \approx 2.915$$
**Final answer:**
$$x \approx 2.915$$
Solve Exponential B08642
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