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Buna ziua ,
Am si eu nevoie de ajutor la:
Sa se rezolve in multimea numerelor reale ecuatia 2x=4radicalx-1 +3.
Multumesc,


Răspuns :

2x=4√(x-1) +3 . x-1≥0
2x-3 =4√(x-1), ridicam la patrat ambii membri si obtinem:
4x^2-28x+25=0, se aplica formula de rezolvare.
Obs. Ce-i sub radical?
[tex]2x=4\sqrt{x-1}+3\\ 2x-3=4\sqrt{x-1}|()^2\\ 4x^2-12x+9=16(x-1)\\ 4x^2-12x+9=16x-16\\ 4x^2-28x+25=0\\ \Delta=784-4*4*25\\ \Delta=384=\ \textgreater \ \sqrt{\Delta}=8\sqrt6\\ x_1=\frac{28-8\sqrt6}{8}\\ x_1=\frac{4(7-2\sqrt6)}{8}\\ x_1=\frac{7-2\sqrt6}{2}[/tex]