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

Toán Lớp 8: tìm x biết a, x² – 8x = 0 b, x² – 12x = -36 c, x² – 4x + 4 = 9 d, (2x+1)² – 4x.(x+3) = 9

Toán Lớp 8: tìm x biết
a, x² – 8x = 0
b, x² – 12x = -36
c, x² – 4x + 4 = 9
d, (2x+1)² – 4x.(x+3) = 9

Comments ( 2 )

  1. Giải đáp: a)   x(x-8)=0
                 th1 x=0
                 th2 x-8=0
                 th1 x=0
                 th2 x=8 
    b) x(x-12)=-36
    th1 x=-36
    th2x-12=-36
    th1x=-36
    th2x=-24
     

  2. a, x² – 8x = 0
    ⇒x(x-8) = 0
    ⇒x=0
    ⇒x-8 = 0 ⇒x=8
    b, x² – 12x = -36
    ⇒x(x-12) = -36
    ⇒x = -36
    ⇒x-12 = -36⇒x= -24
    c, x² – 4x + 4 = 9
    ⇒(x-2)² = 9
    ⇒x-2 =3
    ⇒x = 5
    d, (2x+1)² – 4x.(x+3) = 9
    ⇒4x²+4x+1-4x²-12 = 9
    ⇒4x=20
    ⇒x=5

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

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