giup minh bai nay voi

6

654321sss

Có $A= x - \sqrt{2x-3}$
Xét[TEX] 2A = 2x-2\sqrt{2x-3} = 2x-3 - 2\sqrt{2x-3} +1 +2 = (\sqrt{2x-3} -1 )^2 +2 \geq 2[/TEX]

\Rightarrow [TEX]A\geq1[/TEX] Vậy min A = 1 \Leftrightarrow x = 2
 
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