方程4x2-4x+1=0的解x1=x2=______.
∵4x2-4x+1=0
∴(2x-1)2=0
∴x1=x2=12.
学校普通教室课桌呈规律性排列,宜采用顶棚上均匀布灯的()方式。
A.局部照明
B.一般照明
C.分区一般照明
D.局部照明
()is halfway between the forward and after perpendiculars and is reference point for vessel construction.
A.Half length
B.Mid-body
C.Center line
D.Amidships