[tex]\displaystyle \frac{x^2-16}{3x^2-10x-8}=\frac{(x-4)(x+4)}{3x^2+2x-12x-8}=\frac{(x-4)(x+4)}{x(3x+2)-4(3x+2)}=\frac{(x-4)(x+4)}{(3x+2)(x-4)}=\frac{x+4}{3x+2}[/tex]