234. Determine the necessary and sufficient condition for the value of the fraction $\frac{a x^{2}+b x+c}{a_{1} x^{2}+b_{1} x+c_{1}}$ to remain unchanged for arbitrary values of the letter $x$. Generalize.
234. $\frac{a}{a_{1}}=\frac{b}{b_{1}}=\frac{c}{c_{1}}$ (cf. prob. 232-233).