257. If it is known that the equation

$$
12 x^{5}-8 x^{4}-45 x^{3}+45 x^{2}+8 x-12=0
$$

admits the roots $+1 ; 1.5 ; -2$, write, without any calculations, the two missing roots.
257. It is easy to notice that if $\alpha$ is a root of the given equation, then $\frac{1}{\alpha}$ will also be a root, and therefore the required roots will be $\frac{1}{1.5}=\frac{10}{15}=\frac{2}{3}$ and $\frac{1}{-2}=-\frac{1}{2}$.