Question

Answer 1

a) TH1:|3x|=3x nếu \(3x\ge0\)

<=>3x=x+8

<=>3x-x=8

<=>2x=8

<=>x=4 (t/m)

TH2:|3x|=-3x nếu 3x<0

<=>-3x=x+8

<=>-3x-x=8

<=>-4x=8

<=>x=-2(t/m)

Answer 2

b) TH1:|-2X|=-2X nếu \(-2x\ge0\)

-2x=4x+18

<=>x=-3 (loại)

TH2:|-2X|=2X nếu-2X<0

2X=4X+18

<=>X=-9(T/M)

Answer 3

C)TH1:|X-5|=X-5 nếu X-5\(\ge0\)

<=>X-5=3X

<=>X=-5/2 (Loại)

TH2: |X-5|=-(X-5) nếu x-5<0

<=> -x+5=3x

<=>x=5/4 (t/m)

Answer 4

d)TH1: |x+2|=x-2 nếu x-2\(\ge0\)

<=>x+2=2x-10

<=> x=12(t/m)

TH2: |x+2| =-x-2 nếu x-2<0

<=>-x-2=2x-10

<=>x=8/3(loại)