[tex] \frac{a}{a - b} - \frac{b}{a + b} [/tex]
[tex] = \frac{a(a + b)}{(a + b)(a - b)} - \frac{b(a - b)}{(a + b)(a - b)} [/tex]
[tex] = \frac{a(a + b) - b(a - b)}{(a - b)(a + b)} [/tex]
[tex] = \frac{ {a}^{2} + ab - ab + {b}^{2} }{ {a}^{2} - {b}^{2} } [/tex]
[tex] = \frac{ {a}^{2} + {b}^{2} }{ {a}^{2} - {b}^{2} } [/tex]
