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Wednesday, April 25, 2007
ALGEBRA QUESTION OF THE DAY
An odd number added to itself an odd number of times yields (A) an odd number (B) an even number (C) a prime number (D) a positive number (E) a perfect square
Since pq/2 is prime, it is an integer. Hence, either p or q must be even; otherwise, the 2 would not cancel and pq/2 would be a fraction. The only even prime number is 2. Hence, either p or q, but not both, must be 2. The other one is an odd prime number. Now, the sum of an even number and an odd number is an odd number. The answer is (A).
a
ReplyDeleteA
ReplyDeleteSince pq/2 is prime, it is an integer. Hence, either p or q must be even; otherwise, the 2 would not
ReplyDeletecancel and pq/2 would be a fraction. The only even prime number is 2. Hence, either p or q, but not both,
must be 2. The other one is an odd prime number. Now, the sum of an even number and an odd number is
an odd number. The answer is (A).