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

Toán Lớp 9: $\sqrt{4+$\sqrt{10}$}$-$\sqrt{4-$\sqrt{10}$}$

Toán Lớp 9: $\sqrt{4+$\sqrt{10}$}$-$\sqrt{4-$\sqrt{10}$}$

Comments ( 1 )

  1. Đặt A=\sqrt{4+\sqrt{10}}-\sqrt{4-\sqrt{10}}
    =>A^2=(\sqrt{4+\sqrt{10}}-\sqrt{4-\sqrt{10}})^2
    =4+\sqrt{10}+4-\sqrt{10}+2\sqrt{(4+\sqrt{10})(4-\sqrt{10})}
    =8+2\sqrt{16-10}
    =8+2\sqrt{6}
    Mà A>0
    =>A=\sqrt{8+2\sqrt{6}}

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

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