1. **State the problem:** Solve the equation $$3^x + 9^x + 27^x = 14$$ for the variable $x$.
2. **Rewrite the terms with the same base:** Note that $9 = 3^2$ and $27 = 3^3$, so rewrite the equation as:
$$3^x + (3^2)^x + (3^3)^x = 14$$
which simplifies to:
$$3^x + 3^{2x} + 3^{3x} = 14$$
3. **Substitute:** Let $$y = 3^x$$. Then the equation becomes:
$$y + y^2 + y^3 = 14$$
4. **Rewrite as a polynomial:**
$$y^3 + y^2 + y - 14 = 0$$
5. **Solve the cubic equation:** Try possible rational roots using factors of 14: $\pm1, \pm2, \pm7, \pm14$.
Check $y=2$:
$$2^3 + 2^2 + 2 = 8 + 4 + 2 = 14$$ which satisfies the equation.
6. **Factor the cubic:** Since $y=2$ is a root, divide the cubic by $(y-2)$:
$$y^3 + y^2 + y - 14 = (y-2)(y^2 + 3y + 7)$$
7. **Solve the quadratic:**
$$y^2 + 3y + 7 = 0$$
Calculate discriminant:
$$\Delta = 3^2 - 4 \times 1 \times 7 = 9 - 28 = -19 < 0$$
No real roots here.
8. **Real solution for $y$ is $2$ only.**
9. **Back-substitute for $x$:**
$$3^x = 2$$
Take logarithm base 3:
$$x = \log_3 2 = \frac{\ln 2}{\ln 3}$$
**Final answer:**
$$x = \frac{\ln 2}{\ln 3}$$
Solve Exponential 8492C6
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