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

Toán Lớp 9: Tính `(\sqrt{10}+\sqrt{2})\sqrt{3-\sqrt{5}`

Toán Lớp 9: Tính (\sqrt{10}+\sqrt{2})\sqrt{3-\sqrt{5}

Comments ( 2 )

  1. (\sqrt{10}+\sqrt{2})\sqrt{3-\sqrt{5}}
    =\sqrt{2}(\sqrt{5}+1)\sqrt{3-\sqrt{5}}
    =(sqrt{5}+1)\sqrt{6-2\sqrt{5}}
    =(\sqrt{5}+1)\sqrt{(\sqrt{5})^2-2\sqrt{5}.1+1^2}
    =(\sqrt{5}+1)\sqrt{(\sqrt{5}-1)^2}
    =(\sqrt{5}+1)|\sqrt{5}-1|
    =(\sqrt{5}+1)(\sqrt{5}-1)
    =\sqrt{5^2}-1^2
    =|5|-1
    =5-1
    =4
     

  2. Giải đáp + Lời giải và giải thích chi tiết:
    (\sqrt{10}+\sqrt{2}).\sqrt{3-\sqrt{5}}
    =\sqrt{2}(\sqrt{5}+1).\sqrt{3-\sqrt{5}}
    =(\sqrt{5}+1).\sqrt{6-2\sqrt{5}}
    =(\sqrt{5}+1).\sqrt{(\sqrt{5}-1)^{2}}
    =(\sqrt{5}+1).|\sqrt{5}-1|
    =(\sqrt{5}+1)(\sqrt{5}-1)
    =\sqrt{5}^{2}-1^{2}
    =5-1=4

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