2002 AMC 10A Problem 14

Below is the professionally curated solution for Problem 14 of the 2002 AMC 10A, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2002 AMC 10A solutions, or check the answer key.

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Concepts:Vieta’s Formulasprimeparity

Difficulty rating: 1310

14.

Both roots of the quadratic equation x263x+k=0x^2-63x+k=0 are prime numbers. The number of possible values of kk is

00

11

22

44

more than four

Solution:

If the roots are primes pp and q,q, then p+q=63p+q=63 and pq=k.pq=k. Because 6363 is odd, one prime must be 2,2, making the other 61,61, which is prime.

So k=261=122k=2\cdot 61=122 is the only possible value.

Thus, the correct answer is B.

Problem 14 in Other Years