Question

Giải các phương trình :

a) \(\left|9+x\right|=2x\)

b) \(\left|x-1\right|=3x+2\)

c) \(\left|x+6\right|=2x+9\)

d) \(\left|7-x\right|=5x+1\)

Answer 1

a, TH1: 9+x=2x
      => x-2x=-9
     => -x=-9
     => x=9
TH2: 9+x=-2x
  => x+2x=-9
  => 3x=-9
  =>x=-3
b, TH1: x-1=3x+2
       =>x-3x=2+1
       => -2x=3
      => x=-3/2
 TH2: x-1=-3x-2
    => x+3x=-2+1
   => 4x=-1
    => x=-1/4
c, TH1: x+6=2x+9
     => x-2x=9-6
    => -x=3
   => x=-3
TH2: X+6=-2x-9
    => x+2x=-9-6
    =>3x=-15
    =>x=-5
d, TH1: 7-x=5x+1
       => -x-5x=1-7
      => -6x=-6
      => x=1
TH2: 7-X=-5x-1
     => -x+5x=-1-7
    => 4x=-8
    => x=-2