2 câu trả lời
$\dfrac{1}{\sqrt{5}-1}$$-$$\dfrac{1}{\sqrt{5}+1}$
$=$$\dfrac{\sqrt{5}+1-\sqrt{5}+1}{(\sqrt{5}-1)(\sqrt{5}+1)}$
$=$$\dfrac{2}{5-1}$
$=$$\dfrac{1}{2}$
@Nobitao@
Đáp án:
`\frac{1}{sqrt5-1}-\frac{1}{sqrt5+1}`
`= \frac{sqrt5+1}{(sqrt5-1)(sqrt5+1)}-\frac{sqrt5-1}{(sqrt5+1)(sqrt5-1)}`
`= \frac{sqrt5+1-sqrt5+1}{5-1}`
`= \frac{2}{4}`
`= 1/2`
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