a) in a 2-a paranteza aducem la numitor comun ...
E(x) = (2x+1)/(x-1) : [(1-x^2-3x^2)/(1-x^2)]=
= (2x+1)/(x-1) : (1-4x^2)/(1-x^2) =
= (2x+1)/-(1-x) * (1-x)(1+x)/(1-2x)(1+2x)= (1-x respectiv 2x+1 se simplifica)
= (1+x)/[-1*(1-2x)]=(1-x)/(2x-1) ;
b) (2x-1) * (1+x)/(2x-1)>1,5 (2x-1 se simplifica ...)
ramane ... 1+x > 1,5 de unde x > 1,5-1
deci x > 0,5=1/2 => x e (1/2 ; +infinit)