Răspuns:
Explicație pas cu pas:
x²+5x+6 = (x+2)(x+3)
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E(x) = [ x(x+3) + (x+2)(x+2) - x²-7x] / [(x+2)(x+3)] × (x+3)/(x²+4)
-> amplific fractia x/(x+2) cu (x+3), iar fractia (x+2)/(x+3) o amplific cu (x+2)
E(x) = (x²+3x+x²+4x+4-x²-7x)/(x+2) × 1/(x²+4)
E(x) = (x²+4)/(x+2) × ( 1/(x²+4)
E(x) = 1/(x+2), x ∈R\{-2}
