13.星星果汁店中的A种果汁比B种果汁每杯贵1元,小彬和同学买了3杯B种果汁,2杯A种果汁,一共花了16元,A种果汁B种果汁每杯分别多少元?设A种果汁的单价为x元,B种果汁的单价为y元,则以下方程组正确的是( )
| A. | $\left\{\begin{array}{l}{3x+2y=16}\\{x=y+1}\end{array}\right.$ | B. | $\left\{\begin{array}{l}{2x+3y=16}\\{x=y-1}\end{array}\right.$ | C. | $\left\{\begin{array}{l}{2x+3y=16}\\{x=y+1}\end{array}\right.$ | D. | $\left\{\begin{array}{l}{3x+2y=16}\\{x=y-1}\end{array}\right.$ |
12.利用加减消元法解方程组$\left\{\begin{array}{l}{2x+5y=3①}\\{5x-3y=6②}\end{array}\right.$,下列做法正确的是( )
0 284832 284840 284846 284850 284856 284858 284862 284868 284870 284876 284882 284886 284888 284892 284898 284900 284906 284910 284912 284916 284918 284922 284924 284926 284927 284928 284930 284931 284932 284934 284936 284940 284942 284946 284948 284952 284958 284960 284966 284970 284972 284976 284982 284988 284990 284996 285000 285002 285008 285012 285018 285026 366461
| A. | 要消去y,可以将①×5+②×2 | B. | 要消去x,可以将①×3+②×(-5) | ||
| C. | 要消去y,可以将①×5+②×3 | D. | 要消去x,可以将①×(-5)+②×2 |