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

Toán Lớp 9: 5 / căn 7 + căn 2 – 7 – căn 7 / căn 7 -1

Toán Lớp 9: 5 / căn 7 + căn 2 – 7 – căn 7 / căn 7 -1

Comments ( 2 )

  1. Giải đáp+Lời giải và giải thích chi tiết:
    \frac{5}{\sqrt{7}+\sqrt{2}}-\frac{7-\sqrt{7}}{\sqrt{7}-1}
    =\frac{7-2}{\sqrt{7}+\sqrt{2}}-\frac{\sqrt{7}(\sqrt{7}-1)}{\sqrt{7}-1}
    =\frac{(\sqrt{7}-\sqrt{2})(\sqrt{7}+\sqrt{2})}{\sqrt{7}+\sqrt{2}}-\sqrt{7}
    =\sqrt{7}-\sqrt{2}-\sqrt{7}
    =-\sqrt{2}
     

  2. 5/(\sqrt{7}+\sqrt{2})-(7-\sqrt{7})/(\sqrt{7}-1)
    =(5(\sqrt{7}-\sqrt{2}))/((\sqrt{7}+\sqrt{2})(\sqrt{7}-\sqrt{2}))-(\sqrt{7}(\sqrt{7}-1))/(\sqrt{7}-1)
    =(5(\sqrt{7}-\sqrt{2}))/(5)-\sqrt{7}
    =\sqrt{7}-\sqrt{2}-\sqrt{7}
    =-\sqrt{2}
     

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

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