Simplificati:

a) [tex] \frac{x^2-8}{x^2- 4\sqrt{2}+8 } [/tex] x∈ R/{2√2}
b)[tex] \frac{x^2-25}{x^3-10x^2+25x} [/tex] x∈ R/{ 0;5}
c)[tex] \frac{a^2-5a+6}{a^2+a-6} [/tex] a∈ R/{2;-3}