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

Toán Lớp 8: (5x+2)^2+(4x-3)^2+2(5x-2)(5x+2)-75x+2 khẩn cấp

Toán Lớp 8: (5x+2)^2+(4x-3)^2+2(5x-2)(5x+2)-75x+2 khẩn cấp

Comments ( 2 )

  1. #Sad
    (5x+2)^2+(4x-3)^2+2(5x-2)(5x+2)-75x+2
    = 25x^2+20x+4+16x^2-24x+9+2(25x^2-4)-75x+2
    = 25x^2+20x+4+16x^2-24x+9+50x^2-8-75x+2
    = (25x^2+16x^2+50x^2)+(20x-24x-75x)+(4+9-8+2)
    = 91x^2-79x+7
    \text{→Áp dụng:}
    +) (A+B)^2 = A^2+2AB+B^2
    +) (A-B)^2 = A^2-2AB+B^2
    +) A^2-B^2 = (A-B)(A+B)

  2. (5x+2)² + (4x-3)² + 2(5x-2)(5x+2) – 75x + 2
    = 25x² + 20x + 4 + 16x² – 24x + 9 + 2(25x² – 4) – 75x + 2
    = 41x² – 79x + 15 + 50x² – 8
    = 91x² – 79x + 7
    Mk xin ctlhn nếu dc

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

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