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

Toán Lớp 8: Tính: A)(3X-2Y)³ B)(2X+3Y).(2X-3Y) Ai làm đc tui vote 5 sao????

Toán Lớp 8: Tính:
A)(3X-2Y)³
B)(2X+3Y).(2X-3Y)
Ai làm đc tui vote 5 sao????

Comments ( 2 )

  1. $\color{teal}{\text{#phnn}}$
    a)(3x-2y)^3
    =(3x)^3-3.(3x)^2. 2y+3.3x.(2y)^2-(2y)^3
    =27x^3-54x^2y+36xy^2-8y^3
    b)(2x+3y)(2x-3y)
    =(2x)^2-(3y)^2
    =4x^2-9y^2
    \text{————————————-}
    \text{Áp dụng HĐT:}
    1)(a-b)^3=a^3-3a^2b+3ab^2-b^3
    2)a^2-b^2=(a-b)(a+b)

  2. $\\$
    Giải đáp + giải thích các bước giải :
    $a,\\(3x-2y)^3\\=(3x)^3-3.(3x)^2 . 2y+3.3x.(2y)^2-(2y)^3\\=27x^3 – 3.9x^2.2y + 3.3x.4y^2-8y^3\\=27x^3 -54x^2y + 36xy^2 – 8y^3\\b,\\(2x+3y)(2x-3y)\\=(2x)^2-(3y)^2\\=4x^2 – 9y^2$
     

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

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