1. **State the problem:** Solve the equation $3^x - 2 = 5^{x+1}$ for $x$.
2. **Rewrite the equation:** The equation is $3^x - 2 = 5^{x+1}$.
3. **Express $5^{x+1}$:** Use the property of exponents: $5^{x+1} = 5^x \cdot 5^1 = 5 \cdot 5^x$.
4. **Rewrite the equation:**
$$3^x - 2 = 5 \cdot 5^x$$
5. **Isolate terms:** Move all terms to one side:
$$3^x - 5 \cdot 5^x = 2$$
6. **Rewrite the equation:**
$$3^x - 5 \cdot 5^x - 2 = 0$$
7. **Use substitution:** Let $a = 3^x$ and $b = 5^x$.
8. **Note:** Since $a$ and $b$ are exponential functions with different bases, direct substitution is complicated. Instead, try to solve numerically or by taking logarithms.
9. **Rewrite original equation:**
$$3^x - 2 = 5^{x+1}$$
10. **Take natural logarithm on both sides:**
$$\ln(3^x - 2) = \ln(5^{x+1})$$
11. **Simplify right side:**
$$\ln(5^{x+1}) = (x+1) \ln 5$$
12. **Note:** The left side is $\ln(3^x - 2)$ which is not easily simplified.
13. **Try numerical approach:** Test values of $x$ to find approximate solution.
- For $x=1$: $3^1 - 2 = 1$, $5^{1+1} = 25$, not equal.
- For $x=2$: $3^2 - 2 = 7$, $5^{3} = 125$, not equal.
- For $x=0$: $3^0 - 2 = 1 - 2 = -1$, $5^{1} = 5$, no.
14. **Try $x=-1$:**
$$3^{-1} - 2 = \frac{1}{3} - 2 = -\frac{5}{3}$$
$$5^{0} = 1$$
No.
15. **Try $x=3$:**
$$3^3 - 2 = 27 - 2 = 25$$
$$5^{4} = 625$$
No.
16. **Try $x=0.5$:**
$$3^{0.5} - 2 = \sqrt{3} - 2 \approx 1.732 - 2 = -0.268$$
$$5^{1.5} = 5^{1} \cdot 5^{0.5} = 5 \cdot \sqrt{5} \approx 5 \cdot 2.236 = 11.18$$
No.
17. **Try $x= -0.5$:**
$$3^{-0.5} - 2 = \frac{1}{\sqrt{3}} - 2 \approx 0.577 - 2 = -1.423$$
$$5^{0.5} = \sqrt{5} \approx 2.236$$
No.
18. **Try $x=4$:**
$$3^4 - 2 = 81 - 2 = 79$$
$$5^{5} = 3125$$
No.
19. **Observation:** Left side grows slower than right side for positive $x$.
20. **Try to solve by rewriting:**
$$3^x - 2 = 5^{x+1}$$
$$3^x - 2 = 5 \cdot 5^x$$
$$3^x - 5 \cdot 5^x = 2$$
21. **Divide both sides by $5^x$:**
$$\frac{3^x}{5^x} - 5 = \frac{2}{5^x}$$
22. **Rewrite:**
$$\left(\frac{3}{5}\right)^x - 5 = \frac{2}{5^x}$$
23. **Let $y = \left(\frac{3}{5}\right)^x$ and $z = 5^{-x}$:**
Note that $z = \frac{1}{5^x}$.
24. **Rewrite equation:**
$$y - 5 = 2z$$
25. **But $z = \frac{1}{5^x} = \left(\frac{1}{5}\right)^x$ and $y = \left(\frac{3}{5}\right)^x$.
26. **Since $\frac{3}{5} > \frac{1}{5}$, $y$ decreases slower than $z$ as $x$ increases. Try to find $x$ numerically.**
27. **Try $x=0$:**
$$y = 1, z = 1$$
$$1 - 5 = 2(1) \Rightarrow -4 = 2$$
No.
28. **Try $x=-1$:**
$$y = \left(\frac{3}{5}\right)^{-1} = \frac{5}{3} \approx 1.666$$
$$z = \left(\frac{1}{5}\right)^{-1} = 5$$
$$1.666 - 5 = 2 \times 5 \Rightarrow -3.334 = 10$$
No.
29. **Try $x=1$:**
$$y = \frac{3}{5} = 0.6$$
$$z = \frac{1}{5} = 0.2$$
$$0.6 - 5 = 2 \times 0.2 \Rightarrow -4.4 = 0.4$$
No.
30. **Try $x=2$:**
$$y = \left(\frac{3}{5}\right)^2 = \frac{9}{25} = 0.36$$
$$z = \left(\frac{1}{5}\right)^2 = \frac{1}{25} = 0.04$$
$$0.36 - 5 = 2 \times 0.04 \Rightarrow -4.64 = 0.08$$
No.
31. **Try $x=-2$:**
$$y = \left(\frac{3}{5}\right)^{-2} = \left(\frac{5}{3}\right)^2 = \frac{25}{9} \approx 2.778$$
$$z = \left(\frac{1}{5}\right)^{-2} = 25$$
$$2.778 - 5 = 2 \times 25 \Rightarrow -2.222 = 50$$
No.
32. **Conclusion:** No real solution satisfies the equation because the left side is always less than the right side for all tested values.
33. **Check for extraneous solutions:** The original equation involves $3^x - 2$ which must be positive to take logarithms.
34. **Final answer:** The equation $3^x - 2 = 5^{x+1}$ has no real solution.
**Answer:** No real solution exists for $x$.
Exponential Equation 6D231F
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