173 If an infinite geometric sequence of real numbers with a common ratio $q(|q|<1)$ contains both positive and negative terms, then the ratio of the sum of all positive terms to the sum of all negative terms is $\qquad$ .
$173 q^{-1}$ or $q$. The ratio of the sum of positive terms to the sum of negative terms equals
$a_{1} \cdot\left(1+q^{2}+q^{4}+\cdots\right) / a_{1} \cdot\left(q+q^{3}+q^{5}+\cdots\right)=q^{-1} \quad$ (when $a_{1}>0$), or
$a_{1} \cdot\left(q+q^{3}+q^{5}+\cdots\right) / a_{1} \cdot\left(1+q^{2}+q^{4}+\cdots\right)=q$ (when $a_{1}<0$).