9.若反比例函数y=$\frac{k+2}{x}$的图象位于第二、四象限内,则k的取值范围是( )
| A. | k>-2 | B. | k<0 | C. | k>0 | D. | k<-2 |
5.下列四个式子错误的是( )
| A. | -3$\frac{5}{6}$$<-3\frac{6}{7}$ | B. | -1.38>-1.384 | C. | 4.2>-$\frac{21}{5}$ | D. | -2>-3 |
4.《孙子算经》中有这样一个问题:“今有木,不知长短,引绳度之,余绳四尺五寸;屈绳量之,不足一尺,木长几何?”意思是:“用绳子去量一根木材的长,绳子还余4.5尺;将绳子对折再量木材的长,绳子比木材的长短1尺,问木材的长为多少尺?”若设木材的长为x尺,绳子长为y尺,则根据题意列出的方程组是( )
0 292689 292697 292703 292707 292713 292715 292719 292725 292727 292733 292739 292743 292745 292749 292755 292757 292763 292767 292769 292773 292775 292779 292781 292783 292784 292785 292787 292788 292789 292791 292793 292797 292799 292803 292805 292809 292815 292817 292823 292827 292829 292833 292839 292845 292847 292853 292857 292859 292865 292869 292875 292883 366461
| A. | $\left\{\begin{array}{l}{x-y=4.5}\\{x-\frac{1}{2}y=1}\end{array}\right.$ | B. | $\left\{\begin{array}{l}{y-x=4.5}\\{x-2y=1}\end{array}\right.$ | C. | $\left\{\begin{array}{l}{y-x=4.5}\\{x-\frac{1}{2}y=1}\end{array}\right.$ | D. | $\left\{\begin{array}{l}{y-x=4.5}\\{\frac{1}{2}y-x=1}\end{array}\right.$ |