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

Toán Lớp 9: a)3 căn 2 . 5 căn 6 . 4 căn 12 b) (căn 7 – căn 2 ) ^2 + 2 căn 14 c) ( 1+ căn 5 +căn 6 ) ( 1+ căn 5 -căn 6)

Toán Lớp 9: a)3 căn 2 . 5 căn 6 . 4 căn 12 b) (căn 7 – căn 2 ) ^2 + 2 căn 14 c) ( 1+ căn 5 +căn 6 ) ( 1+ căn 5 -căn 6)

Comments ( 2 )

  1. $@Mốc$
    a) $3\sqrt[]{2}$.$5\sqrt[]{6}$.$4\sqrt[]{12}$ 
    = $3\sqrt[]{2}$.$5\sqrt[]{2}\sqrt[]{3}$.$4\sqrt[]{3}\sqrt[]{4}$ 
    = $3\sqrt[]{2^{2}}$.$5\sqrt[]{3}$.$8\sqrt[]{3}$ 
    = $6$.$5\sqrt[]{3^{2}}$.$8$ 
    = $30.3$.$8$ 
    = $90$.$8$
    = $720$
    b) $(\sqrt[]{7}-\sqrt[]{2})^{2}$ + $2\sqrt[]{14}$ 
    =  $7$ – $2.\sqrt[]{7}$.$\sqrt[]{2}$ + $2$ + $2\sqrt[]{14}$ 
    =  $9$ – $2\sqrt[]{14}$ + $2\sqrt[]{14}$ 
    =        $9$
    c) $( 1 +\sqrt[]{5}+\sqrt[]{6})$.$( 1 +\sqrt[]{5}-\sqrt[]{6})$ 
    = $(1 +\sqrt[]{5})^{2}$ – $6$ 
    = $1$ + $2\sqrt[]{5}$ + $5$ – $6$ 
    = $2\sqrt[]{5}$ 
    *Chú ý: Hằng đẳng thức : $a^{2}$ – $b^{2}$ = $(a + b).(a – b)$
    $#chucbanhoctotnhe;333$
     

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