a, \(\left(1+3x\right)^3=64\Leftrightarrow\left(1+3x\right)^3=4^3\)
\(\Leftrightarrow1+3x=4\Leftrightarrow3x=3\Rightarrow x=1\in Z\)
Vậy x = 1
b, \(\left(11-4x\right)^3=343\Leftrightarrow\left(11-4x\right)^3=7^3\)
\(\Leftrightarrow11-4x=7\Rightarrow4x=11-7\Rightarrow4x=4\Rightarrow x=1\in Z\)
Vậy x = 1
1.
( 1 + 3x )3 = 64
( 1 + 3x )3 = 43
( 1 + 3x ) = 4
3x = 4 - 1
3x = 3
x = 3 : 3
x = 1
2.
( 11 - 4x )3 = 343
( 11 - 4x )3 = 73
( 11 - 4x ) = 7
4x = 11 - 7
4x = 4
x = 4 : 4
x = 1
