9x²-6x+1=25
(3x-1)²=5²
3x-1=5或3x-1=-5
3x=6或3x=-4
x=2或x=-4/3
2.5(x-0.3)²-1.6=0
(x-0.3)²=16/25
x-0.3=0.8或x-0.3=-0.8
x=1.1或x=-0.5