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

Toán Lớp 8: phân tích đa thức thành nhân tử : a. 3x^2 – 6x +9x^3 b. x^2 – 2x- 4y^2 -4y c. x^2 -25 + y^2 + 2xy d. 2x+2y – x^2 -xy e. x^2y – x^3

Toán Lớp 8: phân tích đa thức thành nhân tử :
a. 3x^2 – 6x +9x^3
b. x^2 – 2x- 4y^2 -4y
c. x^2 -25 + y^2 + 2xy
d. 2x+2y – x^2 -xy
e. x^2y – x^3 – 9y + 9x

Comments ( 1 )

  1. Giải đáp:
    a) 3x(x + 1)(3x – 2)
    b) (x + 2y)(x – 2y – 2)
    c) (x + y – 5)(x + y + 5)
    d) (x + y)(2 – x)
    e) (y – x)(x – 3)(x + 3)
    Lời giải và giải thích chi tiết:
    a)
    3x^2 – 6x + 9x^3
    = 3x(x – 2 + 3x^2)
    = 3x(3x^2 + x – 2)
    = 3x(3x^2 + 3x – 2x – 2)
    = 3x[(3x^2 + 3x) – (2x + 2)]
    = 3x[3x(x + 1) – 2(x + 1)]
    = 3x(x + 1)(3x – 2)
    b)
    x^2 – 2x – 4y^2 – 4y
    = (x^2 – 4y^2) – (2x + 4y)
    = [x^2 – (2y)^2] – 2(x + 2y)
    = (x – 2y)(x + 2y) – 2(x + 2y)
    = (x + 2y)[(x – 2y) – 2]
    = (x + 2y)(x – 2y – 2)
    c)
    x^2 – 25 + y^2 + 2xy
    = (x^2 + 2xy + y^2) – 25
    = (x + y)^2 – 5^2
    = [(x + y) – 5][(x + y) + 5]
    = (x + y – 5)(x + y + 5)
    d)
    2x + 2y – x^2 – xy
    = (2x + 2y) – (x^2 + xy)
    = 2(x + y) – x(x + y)
    = (x + y)(2 – x)
    e)
    x^2 y – x^3 – 9y + 9x
    = (x^2 y – x^3) – (9y – 9x)
    = x^2 (y – x) – 9(y – x)
    = (y – x)(x^2 – 9)
    = (y – x)(x^2 – 3^2)
    = (y – x)(x – 3)(x + 3)
    #SunHee

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