lcm (2*x**2+6*x,12*x)

12*x*(x + 3)

solve(12*x**2 + 36*x, x)

diff(12*x**2 + 36*x, x)

series(12*x**2 + 36*x, x, 0, 10)

Experiment with SymPy at SymPy Live.