(2011内蒙古乌兰察布,13,4分)则=
(2011山东日照,15,4分)已知x,y为实数,且满足=0,那么x2011-y2011= .
(2011山东济宁,5,3分)若,则的值为 ( )
A.1 B.-1 C.7 D.-7
(2011四川内江, 6分)已知,则 .
(2011四川凉山州,5,4分)已知,则的值为( )
A. B. C. D.
(2011湖北荆州,13,4分)若等式成立,则的取值范围是 .