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rezolvati ecuatia:

[tex] log_{2}( x^{2} - 4x + 3 ) = log_{2}(3x+21) [/tex]


Răspuns :

x∈(-∞;1)∪(3;∞)
x²-4x+3=3x+21
x²-7x-18=0
Δ=49+72=121
x1=(7-11)/2=-2
x2=(7+12)/2=9
S={-2;9}