（2x+1)^2=3(2x+1)
（2x+1)^2-3(2x+1)=0
(2x+1)(2x+1-3)=0
2x+1=0 2x-2=0
x=-1/2 x=1
(2)(2+x)^2-9=0
(2+x-3)(2+x+3)=0
(x-1)(x+5)=0
x-1=0 x+3=0
x=1 x=-3