b) 3.[52x+1 - (52)x] = 3.100
3( 52x+1-52x) = 3.100
-> 52x+1-52x = 100
mà 53-52= 100
-> 52x+1-52x = 53-52
Vậy x = 1
c) (42)x : 4x = 42
<=>42x-x =42
<=> 4x = 42
-> x=2
d) 2x( 0,5 +4) = 72
2x. 4,5 = 72
2x = 72:4,5 = 16
2x = 24 = 16
-> x= 4