2014 · Q42
If N² − 33, N² − 31 and N² − 29 are prime numbers, then what is the number of possible values of N, where N is an integer?
Elementary MathematicsNumber System
- A1
- B2
- C6
- DNone of the above
Explanation
The three numbers cover all residues mod 3, so one equals 3: N² − 33 = 3 gives N = ±6 (then 5 and 7, both prime) — 2 values.