A:2(x+2)(x﹣1)
B:2(x+2)(x﹣2)(x+1)
C:2(x+2)(x+1)
D:(x+2)(x﹣2)(x+1)
下列“QQ表情”中属于轴对称图形的是( )
已知数列{an}为等比数列,Sn是它的前项和,若a2a3=2a1,且a4与2a7的等差中项为54,则S5= ()
Who is ____ (old) of you three?