Ta có: (2x-5)^3.3=81
=> (2x-5)^3 = 81:3 = 27
Mà 3^3 = 27
=> (2x-5)^3 = 3^3
=> 2x-5 = 3
=> 2x = 8
=> x = 4
( 2x - 5 )^3 = 81 : 3
( 2x - 5 )^3 = 27
( 2x - 5 )^3 = 3^3
2x - 5 = 3
2x = 3 + 5
2x = 8
x = 8 : 2
x = 4
Ta có: (2x-5)^3.3=81
=> (2x-5)^3 = 81:3 = 27
Mà 3^3 = 27
=> (2x-5)^3 = 3^3
=> 2x-5 = 3
=> 2x = 8
=> x = 4
\(\left(2x-5\right)^3.3=81\)
\(\left(2x-5\right)^3.3=3^4\)
\(\left(2x-5\right).3=3\)
\(2x-5=3:3\)
\(2x-5=1\)
\(2x=1+5\)
\(2x=6\)
\(x=6:2\)
\(x=3\)
k mình nhé
(2x - 5)3 . 3 = 81
(2x - 5)3 = 81 : 3
(2x - 5)3 = 27
(2x - 5)3 = 33
=> 2x - 5 = 3
=> 2x = 3 + 5
=> 2x = 8
=> x = 8 : 2
=> x = 4