12.
如图所示,C为线段AE上一动点(不与点A,E重合),在AE同侧分别作正△ABC和正△CDE,AD与BE交于点O,AD与BC交于点P,BE与CD交于点Q,连接PQ.以下四个结论:①△ACD≌△BCE;②AD=BE;③∠AOB=60°;④△CPQ是等边三角形.
其中正确的是( )
其中正确的是( )
| A. | ①②③④ | B. | ②③④ | C. | ①③④ | D. | ①②③ |
11.在$\frac{1}{x}$,$\frac{1}{2}$,$\frac{1}{2}({x^2}+1)$,$\frac{3xy}{π}$,$\frac{3}{x+y}$中,分式的个数为( )
| A. | 2 | B. | 3 | C. | 4 | D. | 5 |
10.下列变形是因式分解的是( )
| A. | x(x+1)=x2+x | B. | x2+2x+1=(x+1)2 | C. | x2+xy-3=x(x+y)-3 | D. | x2+6x+4=(x+3)2-5 |
9.下列各式中与x3n+1相等的是( )
| A. | (x3)n+1 | B. | (xn+1)3 | C. | x3•xn•x | D. | x•x3n |
8.下列计算正确的是( )
0 307829 307837 307843 307847 307853 307855 307859 307865 307867 307873 307879 307883 307885 307889 307895 307897 307903 307907 307909 307913 307915 307919 307921 307923 307924 307925 307927 307928 307929 307931 307933 307937 307939 307943 307945 307949 307955 307957 307963 307967 307969 307973 307979 307985 307987 307993 307997 307999 308005 308009 308015 308023 366461
| A. | x3•x4=x7 | B. | x•x7=x7 | C. | b4•b4=2b8 | D. | a3+a3=2a6 |