【单选题】下列结论中,不正确的有( ) ①反比例函数y= 2 x 的函数值y随x的增大而减小; ②任意三点确定一个圆; ③圆既是轴对称图形又是中心对称图形; ④二次函数y=x 2 -2x-3(x≥1)的函数值y随x的增大而减小; ⑤平分弦的直径垂直于弦; ⑥相等的圆周角所对的弧相等.
【单选题】The teacher, with 6 girls and 8 boys of her class, ________visiting a museum when the earthquake struck. [ ]
【单选题】The teacher, with 6 girls and 8 boys of her class, ______ visiting a museum when the earthquake struck.
【简答题】When visiting the US in 1830s, Alexis de Tocqueville found that the nature of the country was______.
【单选题】知二次函数 的图象如图所示,则下列结论:(1)4a+2b+c>0;(2)方程 两根之和小于零; (3)y随x的增大而增大; (4)一次函数 的图象一定不过第二象限,其中正确的个数是 [ ]
【简答题】已知二次函数y=ax 2 +bx+c的图象与x轴交于(1,0)和(x 1 ,0),其中-2<x 1 <-1,与y轴交于正半轴上一点.下列结论:①b>0;② ac< 1 4 b 2 ;③a>b;④-a<c<-2a.其中所有正确结论的序号是______.
【简答题】The teacher, with 6 girls and 8 boys of her class, ______ visiting a museum when the earthquake struck. A) was B) were C) had been D) would be
【单选题】已知二次函数 y = ax 2 -2 ax -3 a ( a ≠0),关于此函数的图象及性质,下列结论中不一定成立的是( )
B.
该图象与 x 轴的交点为(﹣1,0),(3,0)
C.
若该图象经过点(﹣2,5),则一定经过点(4,5)
【单选题】When we ______ the museum is not decided.
【单选题】已知二次函数y=ax 2 +bx+c(a≠0) 的图象如图所示,则下列结论:(1)4a+2b+c>0; (2)方程ax 2 +bx+c=0两根之和小于零;(3)y随x的增大而增大;(4)一次函数y=x+bc的图象一定不过第二象限。其中正确的个数是 [ ]