15.已知a=log23,b=${log_{\frac{1}{2}}}3$,c=3${\;}^{\frac{1}{2}}$,则( )
| A. | c>b>a | B. | c>a>b | C. | a>b>c | D. | a>c>b |
13.鸡年春节期间,国人发微信拜年已成为一种时尚,若小李的40名同事中,给其发微信拜年的概率为1,0.8,0.5,0的人数分别为8,15,14,3(人),则通常情况下,小李应收到同事的拜年的微信数为( )
| A. | 27 | B. | 37 | C. | 38 | D. | 8 |
12.函数f(x)的图象如图所示,则f(x)的极大值点为( )

| A. | 1 | B. | 2 | C. | 1.7 | D. | 2.7 |
10.△ABC中,边长a、b是方程${x^2}-2\sqrt{3}x+2=0$的两根,且2cos(A+B)=-1则边长c等于( )
0 238948 238956 238962 238966 238972 238974 238978 238984 238986 238992 238998 239002 239004 239008 239014 239016 239022 239026 239028 239032 239034 239038 239040 239042 239043 239044 239046 239047 239048 239050 239052 239056 239058 239062 239064 239068 239074 239076 239082 239086 239088 239092 239098 239104 239106 239112 239116 239118 239124 239128 239134 239142 266669
| A. | $\sqrt{2}$ | B. | $\sqrt{3}$ | C. | 2 | D. | $\sqrt{6}$ |