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

Toán Lớp 8: Tìm x: (x + 2)² + (3x − 1)(3x + 1) − 10x²= 0

Toán Lớp 8: Tìm x: (x + 2)² + (3x − 1)(3x + 1) − 10x²= 0

Comments ( 2 )

  1. (x + 2)² + (3x − 1)(3x + 1) − 10x²= 0
    ⇔x^2+4x+4+(9x^2-1)-10x^2=0
    ⇔x^2+4x+4+9x^2-1-10x^2=0
    ⇔4x+3=0
    ⇔4x=-3
    ⇔x=-3/4
     Vậy x∈{-3/4}
    áp dụng hđt:
    (A+B)^2=A^2+2AB+B^2 và (A+B).(A-B)=A^2-B^2
    mk gửi nha~
    $#chúc tus học tốt!!$
     

  2. Tìm x: (x + 2)² + (3x − 1)(3x + 1) − 10x²= 0
    ⇔x² +4x + 4 + 9x² – 1 -10x² = 0
    ⇔ 4x + 3 =0
    ⇔ 4x = -3
    ⇔x = -3/4
    MÌnh gửi bạn 

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

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