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

Toán Lớp 8: Phân tích đa thức sau thành nhân tử: a, a ² – 9 – 5a + 15 b, 3m ² – 7m – 10

Toán Lớp 8: Phân tích đa thức sau thành nhân tử:
a, a ² – 9 – 5a + 15
b, 3m ² – 7m – 10

Comments ( 2 )

  1. $\#phnn$
    a)a^2-9-5a+15
    =a^2-3^2-5(a-3)
    =(a-3)(a+3)-5(a-3)
    =(a-3)(a+3-5)
    =(a-3)(a-2).
    b)3m^2-7m-10
    =3m^3+3m-10m-10
    =3m(m+1)-10(m+1)
    =(3m-10)(m+1).

  2. a) a ² – 9 – 5a + 15
    = a ² – 3 ² – 5 ( a – 3 )
    = ( a – 3 ) ( a + 3 ) – 5 ( a – 3 )
    = ( a – 3 ) ( a + 3 – 5 )
    = ( a – 3 ) ( a – 2 )
    b) 3 m ² – 7 m – 10
    = 3 m ² – 10 m + 3 m – 10
    = m ( 3 m – 10 ) + ( 3 m – 10 )
    = ( 3 m – 10 ) ( m + 1 )

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