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

Toán Lớp 8: a) 5x(x^2-3xy+4y) b) (2x+3)(x-2) c) (4x-5)(x+2)-3x(x+4) d) (2x-1/2)^2-(x-1/3)(3x-3/4)

Toán Lớp 8: a) 5x(x^2-3xy+4y)
b) (2x+3)(x-2)
c) (4x-5)(x+2)-3x(x+4)
d) (2x-1/2)^2-(x-1/3)(3x-3/4)

Comments ( 2 )

  1. Giải đáp:
    a. 5x^3 -15x^2 y+20xy
    b. 2x^2 -x-6
    c. x^2 -9x-10
    d. x^2 – 1/4 x
    Lời giải và giải thích chi tiết:
    a. 5x(x^2 -3xy+4y)
    =5x.x^2-5x.3xy+5x.4y
    =5x^3-15x^2 y+20xy
    b. (2x+3)(x-2)
    =2x(x-2)+3(x-2)
    =2x^2-4x+3x-6)
    =2x^2 -x-6
    c. (4x-5)(x+2)-3x(x+4)
    =4x^2 +8x-5x-10-3x^2 -12x
    =x^2 -9x-10
    d. (2x- 1/2 )^2 -(x- 1/3 )(3x- 3/4 )
    = 4x^2-2x+1/4-(3x^2-3/4x-x+1/4)
    = 4x^2-2x+1/4-(3x^2-7/4x+1/4)
    = 4x^2-2x+1/4-3x^2+7/4x-1/4
    =x^2 – 1/4 x

  2. Bạn xem ảnh để biết đáp án nha
     

    toan-lop-8-a-5-2-3y-4y-b-2-3-2-c-4-5-2-3-4-d-2-1-2-2-1-3-3-3-4

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