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

Toán Lớp 9: Chứng minh: √(6+4√2) + √(6-4√2) = 4 Giúp mình với nhoaaaaa

Toán Lớp 9: Chứng minh: √(6+4√2) + √(6-4√2) = 4
Giúp mình với nhoaaaaa

Comments ( 2 )

  1. $\sqrt{(6-4\sqrt{2}}$ + $\sqrt{(6+4\sqrt{2}}$ 
    =$\sqrt{(6-2.2\sqrt{2}}$ + $\sqrt{(6+2.2\sqrt{2}}$ 
    = $\sqrt{4 – 2.2\sqrt{2}+ (\sqrt{2})²}$ +  $\sqrt{4 + 2.2\sqrt{2}+ (\sqrt{2})²}$
    = $\sqrt{(2-\sqrt{2})²}$+ $\sqrt{(2+\sqrt{2})²}$
    = |2-$\sqrt{2}$| + |2+$\sqrt{2}$|
    = 2-$\sqrt{2}$ + 2 + $\sqrt{2}$
    = 4(đpcm)
     

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