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

Toán Lớp 8: Tìm x (2x – 3)(2x+3) – (4x + 1)(x-2) + 8 = 20

Toán Lớp 8: Tìm x
(2x – 3)(2x+3) – (4x + 1)(x-2) + 8 = 20

Comments ( 2 )

  1. $ (2x – 3)(2x+3) – (4x + 1)(x-2) + 8 = 20 $
    ⇒(4x^2+6x-6x-9)-(4x^2-8x+x-2)+8=20
    ⇒4x^2-9-(4x^2-8x+x-2)+8=20
    ⇒4x^2-9-4x^2+8x-x+2+8=20
    ⇒(4x^2-4x^2)+(8x-x)+(-9+2+8)=20
    ⇒7x+1=20
    ⇒7x=19
    ⇒x=19/7
    Vậy x=19/7
    $ #tcv $
     

  2. (2x-3)(2x+3)-(4x+1)(x-2)+8=20
    =>4x^2-9-(4x^2-8x+x-2)+8=20
    =>7x+1=20
    =>7x=20-1
    =>7x=19
    =>x=19:7
    =>x=19/7
    Vậy x=19/7

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