Tìm GTLN,GTNN

H

huynhbachkhoa23

Áp dụng bất đẳng thức Cauchy-Schwarz: $|2\sin x+3\cos x|\le \sqrt{13(\sin^2 x+\cos^2 x)}=\sqrt{13}$
Do đó $\sqrt{13}\ge 2\sin x+3\cos x\ge -\sqrt{13}$
hay $\sqrt{13}-7\ge 2\sin x+3\cos x\ge -\sqrt{13}-7$
 
Last edited by a moderator:
You must log in or register to reply here.
Top Bottom