38. $$3^{x-0.5} \cdot 3^{x+1} = 1$$

$$3^{x-0.5} \cdot 3^{x+1} = 1$$ $$3^{x-0.5+x+1} = 1$$ $$3^{2x+0.5} = 3^0$$ $$2x+0.5 = 0$$ $$2x = -0.5$$ $$x = -0.25$$ Ответ: $$\boxed{x=-0.25}$$