Suppose that a uniform metal rod $50 \mathrm{cm}$ long is insulated laterally, and the temperatures at the exposed ends are maintained at $25^{\circ} \mathrm{C}$ and $85^{\circ} \mathrm{C}$, respectively. Assume that an $x-$ axis is chosen as in the accompanying figure and that the temperature $T(x)$ satisfies the equation
$$\frac{d^{2} T}{d x^{2}}=0$$
Find $T(x)$ for $0 \leq x \leq 50$