(x-120)[120-(x-120)]=3200
(x-120)^2-120*(x-120)+3200=0
【(x-120)-40】【(x-120)-80】=0
x-120-40=0 或 x-120-80=0
x=160 或 x=200
(x-120)(120-x+120)=3200
(x-120)(240-x)=40×80
如果 x-120=40或80
则x=160 或 200
360x-x平方-32000=0
(x-200)(x-160)=0
x1=200,x2=160
(X-120-40)(X-120-80)=0