(x-120)(x-130)=1600 分解得 x-250x+14000=0 x=［-b+√(b-4ac)］/2a或 x=［-b-√(b-4ac)］/2a则 x=125+5√65或 x=125-5√65
(X-120)(X-130)=1600
(x-120)(x-130)=1600 分解得 x-250x+14000=0 x=［-b+√(b-4ac)］/2a或 x=［-b-√(b-4ac)］/2a则 x=125+5√65或 x=125-5√65