a) x + 72 = 36
x = 36 - 72
x = - 36
b) 16 x2 = 64
x2 = 64 : 16 = 4
x2 = 22
⇒ x = 2
c) ( 5x – 2 ) – 64 = - 36
5x - 2 = - 36 + 64 = 28
5x = 28 + 2 = 30
x = 30 : 5
x = 6
d) ( 2x - 10 ) . ( 5 – x ) = 0
⇔ 2x - 10 = 0 hoặc 5 - x = 0
2x = 10 hoặc x = 5
x = 5