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

Toán Lớp 8: bài 1 a) (x+2) ³ b) (2 +3y) ³ c) (x-2y) ³ d) (2-3x) ³

Toán Lớp 8: bài 1
a) (x+2) ³
b) (2 +3y) ³
c) (x-2y) ³
d) (2-3x) ³

Comments ( 2 )

  1. Giải đáp:
     
    Lời giải và giải thích chi tiết:
    (x+2)^3 = x^3 + 3.x^2. 2 + 3.x.2^2 + 2^3 = x^3 + 6x^2 + 12x+8
    (2+3y)^3 = (2)^3 + 3.2^2.3y+3.2+(3y)^2+ (3y)^3 = 8 + 36y+54y^2 + 27y^3
    (x-2y)^3 = x^3 – 3. x^2. 2y + 3.x.(2y)^2 + (2y)^3 = x^3 -6x^2 + 12xy^2 – 8y^3
    (2-3x)^3 = (2)^3 – 3.2^2.3x+3.2+(3x)^2- (3x)^3 = 8 -36x+54^2 -27x^3

  2. #tnvt
    a)(x+2)^3
    =x^3+3.x^2 .2+3.x.2^2+2^3
    =x^3+6x^2+12x+8
    b)(2+3y)^3
    =2^3+3.2^2 .3y+3.2.(3y)^2+(3y)^3
    =8+36y+54y^2+27y^3
    c)(x-2y)^3
    =x^3-3.x^2 .2y+3.x.(2y)^2-(2y)^3
    =x^3-6x^2y+12xy^2-8y^3
    d)(2-3x)^3
    =2^3-3.2^2 .3x+3.2.(3x)^2-(3x)^3
    =8-36x+54x^2-27x^3
     

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

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