Three of the terms are [tex]12a^2bc[/tex], [tex]8ab[/tex], and [tex]4a^2cd[/tex]. To find the least common multiple of those 3, note that [tex]12= 2^2(3)[/tex], [tex]8= 2^3[/tex], and [tex]4= 2^2[/tex]. The least common multiple of those three is [tex]2^3(3)= 24[/tex]. The highest power of a is [tex]a^2[/tex] and the highest power of b, c, and d is 1 for all three. So the least common multiple of those three terms is [tex]24a^2bcd[/tex]. We want another term such that the least common multiple of all four terms is [tex]24a^3bc^2d[/tex]. We already have the "24", the "b" and "d", two of the three "a"s, and one of the two "c"s. It looks like we need just one more "a" and one more "c". Any coefficient must be already included in the "24". What is an odd prime number that divides 24?