Answer:
Step-by-step explanation:
Recall that we say that d | a if there exists an integer k for which a = dk. So, let d = gcd(a,b) and let x, y be integers. Let t = ax+by.
We know that [tex]d | a, d | b[/tex] so there exists integers k,m such that a = kd and b = md. Then,
[tex] t = ax+by = (kd)x+(md)y = d(kx+my)[/tex]. Recall that since k, x, m, y are integers, then (kx+my) is also an integer. This proves that d | t.