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

Toán Lớp 8: Bài 10 Phân tích các đa thức sau thành nhân tử a ) 4a^2 – 9 b,3/5x^3y^2-9/4x^2y^3-6xy c ) x^3 – 2x^2 – 9x + 18 d ) 2x^2 – 3x + 1 .

Toán Lớp 8: Bài 10 Phân tích các đa thức sau thành nhân tử
a ) 4a^2 – 9
b,3/5x^3y^2-9/4x^2y^3-6xy
c ) x^3 – 2x^2 – 9x + 18
d ) 2x^2 – 3x + 1 .

Comments ( 2 )

  1. a)4a^2-9
    =(2a)^2-3^2
    =(2a-3)(2a+3)
    b)3/5x^3y^2-9/4x^2y^3-6xy
    =3xy(1/5x^2y-3/4xy^2-2)
    c)x^3-2x^2-9x+18
    =(x^3-2x^2)-(9x-18)
    =x^2(x-2)-9(x-2)
    =(x-1)(x^2-9)
    =(x-1)(x-3)(x+3)
    d)2x^2-3x+1
    =2x^2-2x-x+1
    =(2x^2-2x)-(x-1)
    =2x(x-1)-(x-1)
    =(x-1)(2x-1)

  2. a)
    4a^2 – 9
    = (2a)^2 – 3^2
    = (2a – 3) (2a+3)
    b)
    3/5 x^3y^2 – 9/4 x^2y^3 – 6xy
    = 6xy. (1/10x^2y – 3/8xy^2 – 1)
    c)
    x^3 – 2x^2 – 9x + 18
    = x^2 . (x-2)  – 9. (x-2)
    = (x^2 – 9) . (x-2)
    = (x^2 – 3^2) . (x-2)
    = (x-3).(x+3).(x-2)
    d)
    2x^2 – 3x + 1
    = 2x^2 – 2x – x + 1
    = 2x . (x-1) – (x-1)
    = (2x-1).(x-1)
     

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