7.方程5x+4y=17的解是( )
| A. | $\left\{\begin{array}{l}{x=1}\\{y=3}\end{array}\right.$ | B. | $\left\{\begin{array}{l}{x=2}\\{y=1}\end{array}\right.$ | C. | $\left\{\begin{array}{l}{x=3}\\{y=2}\end{array}\right.$ | D. | $\left\{\begin{array}{l}{x=4}\\{y=1}\end{array}\right.$ |
4.在Rt△ABC中,∠C=90°,AB=15,AC:BC=3:4,则这个直角三角形的面积是( )
| A. | 24 | B. | 48 | C. | 54 | D. | 108 |
1.用配方法解一元二次方程2x2-4x+1=0,变形正确的是( )
0 293760 293768 293774 293778 293784 293786 293790 293796 293798 293804 293810 293814 293816 293820 293826 293828 293834 293838 293840 293844 293846 293850 293852 293854 293855 293856 293858 293859 293860 293862 293864 293868 293870 293874 293876 293880 293886 293888 293894 293898 293900 293904 293910 293916 293918 293924 293928 293930 293936 293940 293946 293954 366461
| A. | (x-$\frac{1}{2}$)2=0 | B. | (x-$\frac{1}{2}$)2=$\frac{1}{2}$ | C. | (x-1)2=$\frac{1}{2}$ | D. | (x-1)2=0 |