4(x-1)=72
x-1=18
x=19
5x-206=64
5x=270
x=54
câu 1: 12.(x-1):3=43+23
12 . (x - 1 ) :3 = 72
12 . ( x - 1 ) = 72 : 3
12 . ( x - 1 ) = 24
x - 1 = 24 : 12
x - 1 = 2
x = 1
Câu 2: 5x - 206 = 24 .4
5x - 206 = 64
5x = 64 + 206
5x = 270
x = 270 : 5
x = 54
Câu 1 :
12 . ( x - 1 ) : 3 = 43 + 23
=> 12 . ( x - 1 ) : 3 = 64 + 8
=> 12 . ( x - 1 ) : 3 = 72
=> 12 . ( x - 1 ) = 72 x 3
=> 12 . ( x - 1 ) = 216
=> x - 1 = 216 : 12
=> x - 1 = 18
=> x = 18 + 1
=> x = 19
Câu 2 :
5x - 206 = 24 . 4
=> 5x - 206 = 24 . 22
=> 5x - 206 = 64
=> 5x = 64 + 206
=> 5x = 270
=> x = 270 : 5
=> x =54
Câu 1:
\(12.\left(x-1\right):3=4^3+2^3\)
\(12.\left(x-1\right):3=64+8\)
\(12.\left(x-1\right):3=72\)
12.(x-1) =72.3
12.(x-1) =216
(x-1) =216:2
(x-1) =18
x =18+1
x =19
Câu 2:
\(5x-206=2^4.4\)
5x-206=16.4
5x-206=64
5x =64+206
5x =270
x =270:5
x =54
^...^ 
^_^
Câu 1:
\(12\cdot\left(x-1\right):3=4^3+2^3\)
\(12\cdot\left(x-1\right):3=72\)
\(12\cdot\left(x-1\right)=72\cdot3\)
\(12\cdot\left(x-1\right)=216\)
\(x-1=216:12\)
\(x-1=18\)
\(x=18+1\)
\(x=19\)
Vậy \(x=19\)
Câu 2:
\(5x-206=2^4\cdot4\)
\(5x-206=64\)
\(5x=64+206\)
\(5x=270\)
\(x=270:5\)
\(x=54\)
Vậy \(x=54\)
