题目
)上是减函数,如果x1 < 0 , x2 > 0 ,
且| x1 | < | x2 | , 则有( )A. f (-x1 ) + f (-x2 ) > 0 |
B.f ( x1 ) + f ( x2 ) < 0 |
| C. f (-x1 ) -f (-x2 ) > 0 | D.f ( x1 ) -f ( x2 ) < 0 |
)上是减函数,如果
且| x1 | < | x2 | , 则有( )A. f (-x1 ) + f (-x2 ) > 0 |
B.f ( x1 ) + f ( x2 ) < 0 |
| C. f (-x1 ) -f (-x2 ) > 0 | D.f ( x1 ) -f ( x2 ) < 0 |