(1)9x^2-16=0
x=±4/3
(2)5(x-2)=125
x-2=±5
x=7或x=-3
(3)(x+根号5)(x-根号5)=2
x²-5=2
x²=7
x=±根号7
(4)18-(x-1)^2=0
x-1=±3根号2
x=1+3根号2或x=1-3根号2