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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 9: 1/ √5-1 – 1/ √5+1 giúp e zới ạ

Toán Lớp 9: 1/ √5-1 – 1/ √5+1
giúp e zới ạ

Comments ( 2 )

  1. $\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@

  2. Giải đáp:
    \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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222-9+11+12:2*14+14 = ? ( )

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