10.解比例.
$\frac{0.7}{x}$=$\frac{14}{5}$ | 8:30=24:x | $\frac{3}{5}$:$\frac{6}{7}$=x:$\frac{5}{4}$ |
$\frac{3}{5}$:x=$\frac{4}{5}$:$\frac{4}{7}$ | $\frac{21}{x}$=$\frac{32}{8}$ | $\frac{4.2}{15}$=$\frac{5.6}{x}$ |
8.表示x和y成正比例的关系式是( )
A. | x+y=k(一定) | B. | x:y=k(一定) | C. | xy=k(一定) | D. | x-y=k(一定) |
7.将一个圆先按3:1放大,再按1:2缩小.这个圆现在的面积是原来的( )
0 157879 157887 157893 157897 157903 157905 157909 157915 157917 157923 157929 157933 157935 157939 157945 157947 157953 157957 157959 157963 157965 157969 157971 157973 157974 157975 157977 157978 157979 157981 157983 157987 157989 157993 157995 157999 158005 158007 158013 158017 158019 158023 158029 158035 158037 158043 158047 158049 158055 158059 158065 158073 199269
A. | $\frac{2}{3}$ | B. | $\frac{3}{2}$ | C. | $\frac{9}{4}$ | D. | $\frac{4}{9}$ |