What is the least common denominator of the expression below? x2 + 6 x2 + 4x − 12 + 7x x2 + 7x + 6?

If your denominators are
  x² + 4x - 12 = (x +6)(x -2)
and
  x² + 7x + 6 = (x +6)(x +1)
Then the common denominator is the product of unique factors:
  (x +6)(x +1)(x -2)