Given the prime factorizations: a=22⋅32⋅5,b=23⋅3⋅7a = 2^2 \cdot 3^2 \cdot 5, \quad b = 2^3 \cdot 3 \cdot 7a=22⋅32⋅5,b=23⋅3⋅7 Compute lcm(a,b)\text{lcm}(a, b)lcm(a,b).
1260
2520
5040
1890