[toán 12] giới hạn ...................

N

ngomaithuy93

TÌm : .....................
[tex]lim_{x--> \frac{\pi}{4}} = tan2x tan(\frac{\pi}{4} - x)[/tex]
[TEX]\lim_{x\to\frac{\pi}{4}}tan2xtan(\frac{\pi}{4}-x)[/TEX]
[TEX]= \lim_{x\to\frac{\pi}{4}}\frac{sin(\frac{\pi}{4}-x)}{cos2x}[/TEX]
[TEX]= \lim_{x\to\frac{\pi}{4}}\frac{sin(\frac{\pi}{4}-x)}{\frac{\pi}{4}-x}.\frac{\frac{\pi}{2}-2x}{sin(\frac{\pi}{2}-2x)}.\frac{\frac{\pi}{4}-x}{\frac{\pi}{2}-2x}[/TEX]
[TEX] = \frac{1}{2}[/TEX]
 
Top Bottom