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Fie expresia E(X) = [tex] \frac{ x^{2} -x-2}{ x^{2} -4} [/tex] + [tex] \frac{x+1}{x+2} [/tex]. Determinați valorile reale ale lui x, pentru care E(X) = 1.

Răspuns :

[tex] \frac{ x^{2} -2x+x-2}{(x-2)(x+2)} + \frac{x+1}{x+2} =1[/tex]
[tex] \frac{x(x-2)+(x-2)}{(x-2)(x+2)} + \frac{x+1}{x+2} =1[/tex]
[tex] \frac{(x-2)(x+1)}{(x-2)(x+2)} + \frac{x+1}{x+2} =1[/tex]
[tex] \frac{x+1}{x+2}+ \frac{x+1}{x+2} =1[/tex]
2x+2=x+2
x=0