15.双曲线的渐近线方程为y=±4x,且焦点在x轴上,则该双曲线的离心率为( )
| A. | 5 | B. | $\sqrt{5}$ | C. | $\sqrt{17}$ | D. | $\sqrt{17}$或$\frac{\sqrt{17}}{2}$ |
14.已知双曲线方程为x2-y2=4,过点A(3,1)作直线l与该双曲线交于M,N两点,若点A恰好为MN中点,则直线l的方程为( )
| A. | y=3x-8 | B. | y=-3x+8 | C. | y=3x-10 | D. | y=-3x+10 |
13.下列命题中假命题是( )
| A. | ?x∈R,lgx=0 | B. | ?x∈R,sinx+cosx=$\sqrt{3}$ | ||
| C. | ?x∈R,x2+1≥2x | D. | ?x∈R,2x>0 |
12.已知命题p:|x+1|>2,命题q:5x-6>x2,则p是q的( )
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| A. | 充分不必要条件 | B. | 必要不充分条件 | ||
| C. | 充要条件 | D. | 既不充分也不必要条件 |