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Valorile lui m∈ R pentru care sistemul are solutie unica [tex] \left \{ {{x-2=y} \atop { x^{2} -mx+2m+1=y}} \right. [/tex] sunt?

Răspuns :

[tex]x^2-mx+2m+1=x-2\\ x^2-x(m+1)+2m+3=0\\ \triangle=0\\ (m+1)^2-4(2m+3)=0\\ m^2+2m+1-8m-12=0\\ m^2-6m-11=0\\ \triangle=36+44=80\\ m_{1/2}=\frac{6\pm\sqrt{80}}{2}=\frac{6\pm4\sqrt{5}}{2}=3\pm2\sqrt{5}[/tex]