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a)
x2−4x−3<6
x2−4x−3<6 −6 ∧ x2−4x−3>−6 +6
(1)x2−4x−9<0 ∧ (2)x2−4x+3>0
(1) x2−4x−9<0
Δ=(−4)2−4⋅1⋅(−9)= 16+36=52
Δ=52=4⋅13=213
x1=24−213=2−13
x2=2+13
x∈(2−13; 2+13)
2−13≈2−3,6=−1,6
2+13≈2+3,6=5,6
(2) x2−4x+3>0
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