a)2x-138=23.32
=>2x-138=72
=>2x =72+138
=>2x =210
=>x =210:2
=>x =105
b)20-[7(x-3)+4]=2
=>7(x-3)+4 =20-2
=>7(x-3)+4 =18
=>7(x-3) =18-4
=>7(x-3) =14
=>x-3 =14:7
=>x-3 =2
=>x =2+3
=>x =5
c)[6x-39].3.28=5628
=>[6x-39].3 =5628:28
=>[6x-39].3 =201
=>6x-39 =201:3
=>6x-39 =67
=>6x =67+39
=>6x =106
=>x =106:6
=>x =17,6
a) \(2x-138=2^2.3^2\)
\(2x-138=4.9\)
\(2x-138=36\)
\(2x=36+138\)
\(2x=174\)
\(x=174:2\)
\(x=87\)
Vậy \(x=87\)
b) \(20-\left[7.\left(x+3\right)+4\right]=2\)
\(\left[7.\left(x+3\right)+4\right]=20-2\)
\(7.\left(x+3\right)+4=18\)
\(7.\left(x+3\right)=18-4\)
\(7.\left(x+3\right)=14\)
\(\left(x+3\right)=14:7\)
\(x+3=2\)
\(x=2-3\)
\(x=-1\)
Vậy \(x=-1\)
c) \(\left[6x-39\right].3.28=5628\)
\(\left[6x-39\right].84=5628\)
\(\left[6x-39\right]=5628:84\)
\(6x-39=67\)
\(6x=67+39\)
\(6x=106\)
\(x=106:6\)
\(x=\frac{53}{3}\)
Vậy \(x=\frac{53}{3}\)
Chúc bạn học tốt !!!
