17.已知{an}各项为正的等比数列,其前n项和为Sn,若a3=4,S3=7,则公比q等于( )
A. | $\frac{1}{2}$ | B. | $\frac{3}{2}$ | C. | 2 | D. | 3 |
15.复数$\frac{-1+3i}{1+i}$=( )
A. | 2+i | B. | 2-i | C. | 1+2i | D. | 1-2i |
12.下列命题中的假命题是( )
A. | ?x∈R,log2x=0 | B. | ?x∈R,x2>0 | C. | ?x∈R,tanx=0 | D. | ?x∈R,3x>0 |
11.在复平面内,复数z=$\frac{3i}{-1+2i}$的共轭复数的虚部为( )
0 250887 250895 250901 250905 250911 250913 250917 250923 250925 250931 250937 250941 250943 250947 250953 250955 250961 250965 250967 250971 250973 250977 250979 250981 250982 250983 250985 250986 250987 250989 250991 250995 250997 251001 251003 251007 251013 251015 251021 251025 251027 251031 251037 251043 251045 251051 251055 251057 251063 251067 251073 251081 266669
A. | $\frac{3}{5}i$ | B. | $-\frac{3}{5}i$ | C. | $-\frac{3}{5}$ | D. | $\frac{3}{5}$ |