daca Δ < 0 ( inecuatia nu are radacini si pastreaza semnul lui a = + 1 peste tot in R )
Δ = ( m -3) ² -4 (m +3) = ( m -3) · ( m -3 -4) = ( m -3) · ( m -7) < 0
m - ∞ 3 7 +∞
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Δ<0 + 0 - 0 +
daca m ∈ ( 3 , 7 )