Proving a polynomial $f(x)$ composite for infinitely many $x$
Solution 1:
Choose $m$ such that $f(m)\ne\pm1$, then choose any prime $p$ dividing $f(m)$, and think about $f(m+pk)$ for $k=1,2,\dots$.
Proving a polynomial $f(x)$ composite for infinitely many $x$
Solution 1:
Choose $m$ such that $f(m)\ne\pm1$, then choose any prime $p$ dividing $f(m)$, and think about $f(m+pk)$ for $k=1,2,\dots$.