(x+3)^2=16
x+3 = ±4
x1 = -3-4 = -7
x2 = -3+4 = 1
【问题补充：对不起我写错了……是(x+3)^2=16x!】
(x+3)^2=16x
x^2+6x+9=16x
x^2-10x+9=0
(x-1)(x-9)=0
x1=1,x2=9