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VTMO 2022 — Grade 9 — vtmo Question 8

VTMO · VTMO 2022 — Grade 9 — vtmo

Question 8

Let $\left[a\right]$ denote the floor. How many integers $n$ make $A = | \left[\frac{5 n^{2} + 9 n + 1}{2}\right] |$ prime?
  1. $1$
  2. $3$
  3. $5$
  4. $7$
  5. $9$