If a and b are prime numbers, such that a > b, which of the following

Answer E. \(a\) must be odd. All primes except 2 are odd. And \(a\) must be greater than \(b\). Thus the only even prime, 2, cannot be \(a\).

An odd base raised to any integral power (even or odd) -- is odd. The expression \(a^{b}\) cannot be even.

Because \(a > b\), the only even power, 2, cannot be "a." There are no prime numbers smaller than 2.

So \(a\) is odd. Its minimum possible value is 3, and all primes greater than 3 are odd.

Rule: An odd base raised to any integer power is always odd. (It is probably easier simply to remember that odd times odd equals odd, and extend that principle.)

Whether an odd number is raised to a power of 2, 3, 4, 5, or 51, the result is odd * odd (* odd * odd . . .) for as many powers as there are. The exponent's even or odd sign is irrelevant. Examples:

If \(a = 3, b = 2\), then \(3^2 = 9\), and odd * odd = odd

If \(a = 5, b = 3\), then \(5^3 = 5 * 5 * 5 = 125\)

Other answer choices can be disproved. Which of following cannot be true?

A. \(a+b\) is prime.
If \(a = 3, b = 2\), \((3 + 2) = 5\). 5 is prime. It can be true. REJECT

B. \(ab\) is odd.
If \(a = 5, b = 3\), \((ab) = 15\), which is odd. Can be true. REJECT

C. \(a(a-b)\) is odd.
If \(a = 3, b = 2\): \((3)(3-2) = (3)(1) = 3\), which is odd. Can be true. REJECT

D. \(a-b\) is prime.
If \(a = 5, b = 3\), \((5 - 3) = 2\), which is prime. Can be true. REJECT

ANSWER E