(x-4)²=4
(x-4)²-4=0
(x-4)²-2²=0
(x-4-2)(x-4+2)=0
(x-6)(x-2)=0
x=6 或 x=2
1/3(x+3)³-9=0
1/3(x+3)³=9
(x+3)³=27=3³
x+3=3
x=0