2 câu trong Đề thi thử 2014 Toan hoc va tuổi trẻ

T

tuonghuy333_2010

Giải đáp

Câu 6:
[TEX]\\ \\ P \geq \frac{16\sqrt{3}}{xy+yz+zx}+\frac{xy+yz+zx+1}{\sqrt{3+2(xy+yz+zx)}} \\ \\ t=xy+yz+zx,0<t \leq 3 \\ \\ P \geq \frac{16\sqrt{3}}{t}+\frac{t+1}{\sqrt{3+2t}} \\ \\ \Rightarrow minP=\frac{4+16\sqrt{3}}{3} \Leftrightarrow x=y=z=1[/TEX]
 
N

nguyenbahiep1

[laTEX]\lim_{ x \to 0} \frac{ln (1+sin^2x)}{sin^2x}.\frac{x}{e^x-1}.\frac{sin^2x}{x^2} = 1[/laTEX]
 
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