Question

下列函數(shù)是偶函數(shù)且在(-∞,0)上為減函數(shù)的是(    )

A.y=                 B.y=x²                 C.y=x³                  D.y=x^-2

Answer 1

解析：函數(shù)y=和y=x³是奇函數(shù)，排除A、C；函數(shù)y=x²和y=x^-2都是偶函數(shù)，由冪函數(shù)的性質(zhì)可知，y=x^-2在(-∞,0)上為增函數(shù)，函數(shù)y=x²在(-∞,0)上為減函數(shù).故選B.

答案：B