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

Toán Lớp 8: Bài1: Phân tích đa thức thành nhân tử. a/ 14x2y – 21xy2 + 28x2y2 b/ x(x + y) – 5x – 5y. c/ 10x(x – y) – 8(y – x). d/ (3x +

Toán Lớp 8: Bài1: Phân tích đa thức thành nhân tử.
a/ 14x2y – 21xy2 + 28x2y2 b/ x(x + y) – 5x – 5y.
c/ 10x(x – y) – 8(y – x). d/ (3x + 1)2 – (x + 1)2
e/ x2 – 16 – 4xy + 4y2 f/ x5 – x4 + x3 – x2
g/ x2 – 6x + 8 h/ 2×2 – x – 1

Comments ( 1 )

  1. Giải đáp:
    a, 14x^2y – 21xy^2 + 28x^2y^2
    =7xy.(2x-3y+4xy)
    —————————
    b, x.(x + y) – 5x – 5y
    =x.(x+y)-5.(x+y)
    =(x+y).(x-5)
    —————————
    c, 10x.(x – y) – 8.(y – x)
    = 10x.(x-y) +8.(x-y)
    = (x-y).(10x+8)
    = 2.(x – y).(5x + 4)
    —————————
    d, (3x + 1)^2 – (x + 1)^2
    = [3x + 1 – (x + 1)].[3x + 1 + x + 1]
    = (3x + 1 – x – 1).(3x + 1 + x + 1)
    = 2x.(4x + 2)
    = 4x.(2x + 1)
    —————————
    e, x^2 – 16 – 4xy + 4y^2
    = (x^2 – 4xy + 4y^2) – 16
    = [x^2 – 2.x.2y + (2y)^2] – 4^2
    = (x-  2y)^2 – 4
    = (x – 2y – 4).(x – 2y + 4)
    —————————
    f, x^5 – x^4 + x^3 – x^2
    = x^2.(x^3 – x^2 + x – 1)
    = x^2.[x^2.(x – 1) + (x – 1)]
    = x^2.(x – 1).(x^2 + 1)
    —————————–
    g, x^2 – 6x + 8
    = x^2 – 4x – 2x + 8
    = x.(x – 4)  -2.(x – 4)
    = (x – 4).(x – 2)
    —————————–
    h, 2x^2 – x – 1
    = 2x^2 + x – 2x – 1
    = x.(2x + 1) – (2x + 1)
    = (2x + 1).(x – 1)
    #dariana

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

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