# How many lines can pass through two given points?

Geometry Level pending

If the circles $$x^{2}+y^{2}+2ax+cy+a=0$$ and $$x^{2}+y^{2}-3ax+dy-1=0$$ intersect in two distinct points $$P$$ and $$Q$$, then the line $$5x+by-a=0$$ passes through $$P$$ and $$Q$$ for $$\text{__________}$$.

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