inecuatie = studiu de semn
x² - 5x + 6 = 0 ; Δ = ( -5)² - 4 ·1·6 = 25 -24 = 1
x₁ = ( 5 - 1) / 2 = 4 /2 = 2
x₂ = (5 + 1) /2 = 6 /2 = 3 ( identic)
semn = tabel
ecuatia : a = + 1
x - ∞ 2 3 +∞
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x²-5x+6 ≤0 + 0 -- 0 +
negativ
daca x∈ [2 ; 3 ]