MHB Prove that if p and q are positive distinct primes, then log_p(q) is irrational.

AI Thread Summary
To prove that if p and q are positive distinct primes, then log_p(q) is irrational, a proof by contradiction is used. Assuming log_p(q) is rational leads to the equation p^(m/n) = q, which can be rewritten as p^m = q^n. This implies that p^m equals q raised to a power, suggesting that both sides are powers of the same base. However, since p and q are distinct primes, this equality cannot hold, confirming that log_p(q) must be irrational. The conclusion reinforces the uniqueness of prime factorization, which prohibits such an equality.
KOO
Messages
19
Reaction score
0
Prove that if p and q are positive distinct primes,then $\log_p(q)$ is irrational.

Attempt:

Proof by contradiction: Assume $\log_p(q)$ is rational.Suppose $\log_p(q) = \dfrac{m}{n}$ where $m,n \in \mathbb{Z}$ and $\gcd(m,n) = 1$.

Then, $p^{\frac{m}{n}} = q$ which implies $p^m = q^n$.
 
Physics news on Phys.org
KOO said:
Prove that if p and q are positive distinct primes,then $\log_p(q)$ is irrational.

Attempt:

Proof by contradiction: Assume $\log_p(q)$ is rational.Suppose $\log_p(q) = \dfrac{m}{n}$ where $m,n \in \mathbb{Z}$ and $\gcd(m,n) = 1$.

Then, $p^{\frac{m}{n}} = q$ which implies $p^m = q^n$.

Almost there! Can $p^m=q^n$ happen for any two distinct primes?
 
Back
Top