Express 72,84 and 105 as the products of prime factors,then use the result ,find the H.C.F and the L.C.M of 72,84 and 105.请说一下如何做？要步骤，谢谢!?

72 = 2³ * 3²
84 = 2² * 3 * 7
105 = 3 * 5 * 7

H.C.F. = 3
L.C.M. = 2³ * 3² * 5 * 7 = 2520

(H.C.F. is the product of all common factors in the lowest power, i.e. H.C.F. = 2⁰ * 3¹ * 5⁰ * 7⁰ = 3)
(L.C.M. is the product of all common factors in the highest power, i.e. L.C.M. = 2³ * 3² * 5 * 7 = 2520)

非常感谢

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