(2x-5)/(3x-1) - (2x+3)/(3x+1) +(2x+8)/(9x²-1)=
(2x-5)/(3x-1) - (2x+3)/(3x+1) +(2x+8)/[(3x-1)(3x+1)]=
Aducem la acelasi numitor comun (3x-1)(3x+1):
(2x-5)(3x+1)/[(3x-1)(3x+1)] - (2x+3)(3x-1)/[(3x+1)(3x-1)]
+(2x+8)/[(3x-1)(3x+1)]=
(6x^2 +2x-15x-5-6x^2+2x-9x+3+2x+8)/[(3x-1)(3x+1)]=
(-18x+6)/[(3x-1)(3x+1)]=
(-6)(3x-1)/[(3x-1)(3x+1)]=
simplificam prin 3x-1:
=(-6)/(3x+1)