Question

方程4x²+Ry²=1的曲线是焦点在y轴上的椭圆，则R的取值范围是

A.R>0                                                             B.0<R<2

C.0<R<4                                                         D.2<R<4

Answer 1

C

解析:

将方程变为+=1,由已知可得<,∴0<R<4.