lcm(x,y,...)
i1 : lcm(-6,15,14) o1 = 210
i2 : lcm(-6/7,15,14) o2 = 210 o2 : QQ
i3 : R = QQ[a..d];
i4 : lcm(a^2-d^2,(a-d)*(b+c)) 2 2 2 2 o4 = a b + a c - b*d - c*d o4 : R
i5 : factor oo o5 = (b + c)(a - d)(a + d) o5 : Expression of class Product
The object lcm is an associative binary method function.