a) x . x . x = 125
x3 =125
x3 = 53
= > x = 5
b) ( x + 500 ) = 1000 - 200 . 2
x + 500 = 1000 - 400
x + 500 = 600
x = 600 - 500
x = 100
c) [( x + 10 ) . 100 ] = 500 + 500 . 10
( x + 10 ) . 100 = 500 + 5000
( x + 10 ) . 100 = 5500
x + 10 = 5500 : 100
x + 10 = 55
x = 55 - 10
x = 45