Question

dau 5 stele va rogg!!!​

Answer 1

Explicație pas cu pas:

1)

${(a - b)}^{2} \geqslant 0 \iff {a}^{2} - 2ab + {b}^{2} \geqslant 0 \\ {a}^{2} + {b}^{2} \geqslant 2ab \iff \frac{{a}^{2} + {b}^{2}}{ab} \geqslant 2 \\ \frac{{a}^{2}}{ab} + \frac{ {b}^{2}}{ab} \geqslant 2 \implies \boxed {\bf \frac{a}{b} + \frac{b}{a} \geqslant 2}$