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Aratati ca urmatoarele relatii sunt adevarate,oricare ar fi xER:
a)x²+64≥16x
b)-10x≤x²+25


Răspuns :

[tex]a)~x^2+64 \geq 16x \Leftrightarrow x^2-16x+64 \geq 0 \Leftrightarrow (x-8)^2 \geq 0,~adevarat! \\ \\ b)~-10x \leq x^2+25 \Leftrightarrow 0 \leq x^2+10x+25 \Leftrightarrow 0 \leq (x+5)^2,~adevarat![/tex]