若等差数列{}的前5项和="25," 且="3," 则= ( )
已知在区间上递增,则实数的取值范围是A. B. C. D.
复数的共轭复数为
设已知集合,,则集合=
若,则方程在上恰好有( )个根.
已知函数满足:,,则++++的值为( )