Question

Determinați valoarea minima a expresiei E=2x^2 +5

Answer 1

$\\ \\ Stim ca \text{x}^2\geq0,\quad \forall \text{x}\in \mathbb_{R} \\ \\ \text{x}^2 \geq0\Big|\cdot 2 \\ \\ 2\text{x}^2\geq0\Big|+5 \\ \\ 2\text{x}^2+5\geq5\\ \\ \Rightarrow Valoarea minima a expresiei 2\text{x}^2+5 este 5.$