设 $a = kx, b = ky$。则 $\gcd(a, b) = k$,$\text{lcm}(a, b) = kxy$。所以 $\gcd(a, b) \times \text{lcm}(a, b) = k^2 x y = a \times b$。
设 $a = kx, b = ky$。则 $\gcd(a, b) = k$,$\text{lcm}(a, b) = kxy$。所以 $\gcd(a, b) \times \text{lcm}(a, b) = k^2 x y = a \times b$。