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

Toán Lớp 8: Bài 1 : (x+3)^2 – ( 2x+6) .( x-3)+( x-3)^2

Toán Lớp 8: Bài 1 : (x+3)^2 – ( 2x+6) .( x-3)+( x-3)^2

Comments ( 2 )

  1. (x + 3)^{2} – (2x + 6)(x – 3) + (x – 3)^{2}
    = (x + 3)^{2} – 2(x + 3)(x – 3) + (x – 3)^{2}
    = (x + 3 – x + 3)^{2}
    = 6^{2}
    = 36
    Áp dụng hằng đẳng thức thứ 2
     

  2. Bạn tham khảo !
    (x+3)^2 – ( 2x+6) .( x-3)+( x-3)^2
    =(x+3)^2-2(x+3)(x-3)+(x-3)^2
    =(x+3-x+3)^2
    =6^2
    =36
     

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