(3x+6)+(x-9)=x+12
3x+6+x-9=x+12
3x+x-x=12-6-9
3x=-3
x=-3:3
x=-1
vậy x=-1
(3x+6)+(x-9)=x+12
<=> 3x+6+x-9=x+12
<=> 4x-3=x+12
<=> 4x-x=12+3
<=> 3x=15
<=>x=5
\(\left(3x+6\right)+\left(x-9\right)=x+12\)
\(3x+6+x-9=x+12\)
\(\Rightarrow3x-x-x=12-6+9\)
\(\Rightarrow x=15\)
vậy\(=15\)
Học tốt
\(\left(3x+6\right)+\left(x-9\right)=x+12\)
\(3x+6+x-9=x+12\)
\(4x-3=x+12\)
\(4x-x=12+3\)
\(3x=15\)
\(x=5\)
Vậy\(x=5\)
