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

Toán Lớp 6: Đề nâng cao nên hơi khó : `7x-x`=`5^21`:`5^19`+`3 ·2^2`-`7`

Toán Lớp 6: Đề nâng cao nên hơi khó :
7x-x=5^21:5^19+3 ·2^2-7

Comments ( 2 )

  1. 7x – x = 5^21 : 5^19 + 3 . 2^2 – 7
    => 6x = 5^2 + 3 . 4 – 7
    => 6x = 25 + 12 – 7
    => 6x = 30
    => x = 30 : 6
    => x = 5
     

  2. Giải
    ${7x−x=5^ {21} ÷5 ^ {19} +3⋅2 ^ 2 −7}$
    $⇔{7x−x=5^ 2 +3×2 ^ 2 −7}$
    $⇔{6x=5^ 2 +3×2^ 2 −7}$
    $⇔{6x=25+3×2^ 2 −7}$
    $⇔{6x=25+3×4−7}$
    $⇔{6x=25+12−7}$
    $⇔{6x=37−7}$
    $⇔{6x=30}$
    $⇔x=\dfrac{30}{6}$
    $⇔x=5$
     

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