Find the least common denominator (LCD) of:

$\frac{x + 2}{x^2 - 1} + \frac{x^2 - 9}{7x - 7}$

Factor each denominator:

$x^2 - 1 = (x - 1)(x + 1)$

$7x - 7 = 7(x - 1)$

The LCD must contain each factor at its highest power:

• Factor $(x - 1)$: appears once in both
• Factor $(x + 1)$: appears in the first denominator
• Factor $7$: appears in the second denominator

$\text{LCD} = 7(x - 1)(x + 1)$