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

Toán Lớp 9: ${2\sqrt{ 4x-8 } -\frac{ 2 }{ 3 } \sqrt{ 9x-18 } = \sqrt{ 49x-98 } -10}$

Toán Lớp 9: ${2\sqrt{ 4x-8 } -\frac{ 2 }{ 3 } \sqrt{ 9x-18 } = \sqrt{ 49x-98 } -10}$

Comments ( 2 )

  1. $ 2\sqrt[]{4x -8 } – \dfrac{2}{3} \sqrt[]{9x-18} = \sqrt[]{49x-98} -10 $      $( x ≥ 2 ) $
    $ ⇒ 2 \sqrt[]{4 ( x – 2 ) } – \dfrac{2}{3} \sqrt[]{9 ( x – 2 )} – \sqrt[]{49 ( x – 2 )} = -10 $
    $ ⇒ 4\sqrt[]{x-2} – 2\sqrt[]{x-2} – 7\sqrt[]{x-2} = -10$
    $ ⇒ – 5\sqrt[]{x-2} = – 10 $
    $ ⇒ \sqrt[]{x-2} = 2 $
    $ ⇒ x – 2 = 4 $
    $ ⇒ x = 6 ( thỏa mãn ) $
    Vậy phương trình có nghiệm $ x = 6 $

  2. ${ 2\sqrt{ 4x-8 } -\dfrac{ 2 }{ 3 } \sqrt{ 9x-18 } = \sqrt{ 49x-98 } -10}$     ${ĐKXĐ: x≥2}$
    ${ ⇔2\sqrt{ 4(x-2) } -\dfrac{ 2 }{ 3 } \sqrt{ 9(x-2) } – \sqrt{ 49(x-2) }=  -10}$
    ${⇔ 4\sqrt{ x-2 } -2\sqrt{ x-2 } – 7\sqrt{ x-2 }=  -10}$
    ${ ⇔-5\sqrt{ x-2 }=  -10}$
    ${ ⇔\sqrt{ x-2 }=2}$
    ${⇔x – 2 = 4}$
    ${⇔x = 6 ,tm}$
    Vậy ${x=6}$
     

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