[tex]\it E(x)= x^2-5-x^2-3x+2x+6=1-x\\ \\ (a-b)(a+b)=a^2-b^2[/tex]
Răspuns:
la 2 se vede doar a
E(x)=x^2-5-(x^2+x-6)=x^2-5-x^2-x+6= 1-x
am folosit
a^2-b^2=(a+b)(a-b)
