a)5.x.(1-2.x)-3.x.(x+18)=0
x.[5.(1-2.x)-3.(x+18)] =0
x.[5- 10.x -3.x -54] =0
x.[-13.x-49] =0
=>x=0 hoặc -13.x-49=0
x=0 hoặc x = -49/13
b)5.x-3{4.x-2[4.x-3(5.x-2)]}=182
5.x-3{4.x-2[-11.x+6]} =182
5.x-3{26.x-12} =182
5.x-78.x+36 =182
x.(5-78) = 146
-73.x =146
x = 2