Bài 1:
a) 3^6 : 3^2 = 3^6-2 = 3^4
b) 5^2012 : 5^2012 = 1
c) 25^4 : 5^2 = 25^4 : 25 = 25^3
Bài 2:
2^2 x 16 x 2^3 = 2^2 x 2^4 x 2^3
= 2^9
Bài 3:
a) 91 - 5 × ( 5 + x ) = 61
5 × ( 5 + x ) = 91 - 61
5 × ( 5 + x ) = 30
5 + x = 30 : 5
5 + x = 6
x = 6 - 5
x = 1
Vậy x = 1
b) [ ( x + 34 ) - 50 ] × 2 = 56
( x + 34 ) - 50 = 56 : 2
( x + 34 ) - 50 = 28
x + 34 = 28 + 50
x + 34 = 78
x = 78 - 34
x = 44
Vậy x = 44