11.已知集合A={1,3,x},B={x2,1},由集合A与B的所有元素组成集合{1,3,x},这样的实数x共有( )
| A. | 1个 | B. | 2个 | C. | 3个 | D. | 4个 |
10.下列不等式中无解的是( )
| A. | x2+2x-1≤0 | B. | x2+4x+4≤0 | C. | 4-4x-x2<0 | D. | 2-3x+2x2≤0 |
7.已知函数f(x)=$\left\{{\begin{array}{l}{1\;\;\;\;\;\;x≥a}\\{0\;\;\;\;\;\;x<a}\end{array}}$,函数g(x)=x2-x+1,则函数h(x)=g(x)-f(x)有两个零点的充要条件为( )
0 251777 251785 251791 251795 251801 251803 251807 251813 251815 251821 251827 251831 251833 251837 251843 251845 251851 251855 251857 251861 251863 251867 251869 251871 251872 251873 251875 251876 251877 251879 251881 251885 251887 251891 251893 251897 251903 251905 251911 251915 251917 251921 251927 251933 251935 251941 251945 251947 251953 251957 251963 251971 266669
| A. | a≤0 | B. | a≥0 | C. | a≤1 | D. | a≥1 |