Cosh Equation 1D8992
1. The problem states: If $\cosh(x) = 2$, find the value of $x$.
2. Recall the definition of hyperbolic cosine:
$$\cosh(x) = \frac{e^x + e^{-x}}{2}$$
3. Set up the equation:
$$\frac{e^x + e^{-x}}{2} = 2$$
4. Multiply both sides by 2:
$$e^x + e^{-x} = 4$$
5. Let $y = e^x$, then $e^{-x} = \frac{1}{y}$, so:
$$y + \frac{1}{y} = 4$$
6. Multiply both sides by $y$ to clear the fraction:
$$y^2 + 1 = 4y$$
7. Rearrange to form a quadratic equation:
$$y^2 - 4y + 1 = 0$$
8. Solve the quadratic using the quadratic formula:
$$y = \frac{4 \pm \sqrt{16 - 4}}{2} = \frac{4 \pm \sqrt{12}}{2} = \frac{4 \pm 2\sqrt{3}}{2} = 2 \pm \sqrt{3}$$
9. Recall $y = e^x$, so:
$$e^x = 2 \pm \sqrt{3}$$
10. Take the natural logarithm of both sides:
$$x = \ln(2 \pm \sqrt{3})$$
11. Therefore, the solutions are:
$$x = \ln(2 + \sqrt{3}) \quad \text{or} \quad x = \ln(2 - \sqrt{3})$$
12. Among the options, this corresponds to option b: $\ln(2 \pm \sqrt{3})$.
Final answer: $x = \ln(2 \pm \sqrt{3})$