2x . 2x + 1 = 128
2x . 2x . 21 = 128
2x . 1 . 2x . 2 = 128
2x . ( 1 . 2) = 128
2x . 2 = 128
2x = 128:2
2x =64
2x = 26
=> x = 6
Kb nha
CHÚC BẠN HỌC TỐT!
2x . 2x + 1 = 128
2x + ( x+ 1 ) = 27
x + ( x + 1 ) = 7
2x + 1 = 7
2x = 7 - 1 = 6
x = 6 : 2 = 3
vậy ...
\(2^x\cdot2^{x+1}=128\)
\(2^{x+x+1}=128\)
\(2^{2x+1}=2^7\)
\(\Rightarrow2x+1=7\)
\(\Rightarrow2x=6\)
\(\Rightarrow x=3\)
Vậy x = 3