6.若实数x,y满足不等式组$\left\{\begin{array}{l}{x+y≥0}\\{x+2y-4≤0}\\{x-my-1≤0}\end{array}\right.$,且x+y的最大值为3,则实数m=( )
| A. | -1 | B. | $\frac{1}{2}$ | C. | 1 | D. | 2 |
20.A(a,a′),B(b,b′)是圆x2+y2=2上任意的两点,若ab+a′b′=-1,则线段AB的长是( )
0 250973 250981 250987 250991 250997 250999 251003 251009 251011 251017 251023 251027 251029 251033 251039 251041 251047 251051 251053 251057 251059 251063 251065 251067 251068 251069 251071 251072 251073 251075 251077 251081 251083 251087 251089 251093 251099 251101 251107 251111 251113 251117 251123 251129 251131 251137 251141 251143 251149 251153 251159 251167 266669
| A. | $\sqrt{6}$ | B. | $\sqrt{2}$ | C. | 2 | D. | $\sqrt{4-2\sqrt{2}}$ |