Toán Lớp 7: tìm x
|2x-5|=x+1
|4+2x|=-4x
|2x-5|+x=2
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Toán Lớp 7: tìm x
|2x-5|=x+1
|4+2x|=-4x
|2x-5|+x=2
Comments ( 2 )
TH1: 2x-5 ≥0
=> x≥5/2
Ta có: |2x-5|=x+1
<=> 2x-5=x+1
<=> x=6
TH2: 2x-5<0
=> x<5/2
Ta có: |2x-5|=x+1
<=> 5-2x=x+1
<=> x=4/3
|4+2x| = -4x
=> x ≤0
TH1: x = 0
<=> |4+2x| = -4x
<=>4 + 0 = 0
=> vô nghiệm
TH2: x < 0
=>(1)x < -2
<=> |4+2x| = -4x
<=> – 4 – 2x = -4x
<=> – 4 = -2x
<=> 2 = x
(2) -2 < x < 0
<=> |4+2x| = -4x
<=> 4 + 2x = -4x
<=> 4 = – 6x
<=> x = -2/3
|2x-5|+x=2
=> |2x-5|=2-x
TH1:2x-5=2-x
=> 2x+x=2+5
=> 3x=7
=> x=7/3
TH2: 2x-5=-(2-x)
=> 2x-5=x-2
=> 2x-x=-2+5
=> x=3