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

Toán Lớp 8: Bài 5: $a) 4x^{2} -4x=-1 \\ c) (4x-1)^{2}- (2x-3)^{2}=0$

Toán Lớp 8: Bài 5:
$a) 4x^{2} -4x=-1 \\ c) (4x-1)^{2}- (2x-3)^{2}=0$

Comments ( 2 )

  1. Bài 5:
    a)4x^2−4x=−1
    ⇔4x^2−4x+1=0
    ⇔(2x−1)^2=0
    ⇔2x−1=0(vì 2 TH có kết quả giống nhau)
    ⇔2x=0+1
    ⇔2x=1
    ⇔x=1/2
    Vậy:x=1/2
    c)(4x−1)^2−(2x−3)^2=0
    [(4x−1)+(2x−3)][(4x−1)−(2x−3)]=0
    (4x−1+2x−3).(4x−1−2x+3)=0
    (6x−4).(2x+2)=0
    TH1:6x−4=0
    6x=0+4
    6x=4
    x=4:6
    x=2/3
    TH2:2x+2=0
    2x=0−2
    x=−2
    x=−2:2
    x=−1
    Vậy :x=2/3 hoặc -1

  2. a)4x^2-4x=-1
    4x^2 – 4x +1=0
    (2x-1)^2=0
    2x-1=0
    2x=0+1=1
    x=1/2
    b)(4x-1)^2 – (2x-3)^2=0
    [(4x-1)+(2x-3)].[(4x-1)-(2x-3)]=0
    (4x-1+2x-3).(4x-1-2x+3)=0
    (6x-4).(2x+2)=0
    TH1: 6x-4=0
    6x=0+4=4
    x=4:6=2/3
    TH2:2x+2=0
    2x=0-2=-2
    x=-2:2=-1
    Vậy…..
     

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

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