x^{(a – b) (a + b)} × x^{(b – c) (b + c)} × x^{(c – a) (c + a)}

= x^{a.a - b.b} × x^{b.b – c.c} × x^{c.c – a.a}

= x^{a.a – b.b + b.b – c.c + c.c – a.a}

= x^o = 1