[Toán 9]Tìm GTNN (GTLN)

T

tranvanhung7997

Theo BĐT Cô si:
$\dfrac{x}{2} + \dfrac{18}{x} \ge 2.\sqrt[]{\dfrac{18}{2}} = 6$
Dấu = có <=> $\dfrac{x}{2} = \dfrac{18}{x}$ <=> $ x^2 = 36$
<=> $x = 6$ vì x > 0
 
You must log in or register to reply here.
Top Bottom