4.我国古代数学名著《孙子算经》中记载了一道题,大意是:100匹马恰好拉了100片瓦,已知1匹大马能拉3片瓦,3匹小马能拉1片瓦,问有多少匹大马、多少匹小马?若设大马有x匹,小马有y匹,那么可列方程组为( )
| A. | $\left\{\begin{array}{l}{x+y=100}\\{3x+3y=100}\end{array}\right.$ | B. | $\left\{\begin{array}{l}{x+y=100}\\{x+3y=100}\end{array}\right.$ | ||
| C. | $\left\{\begin{array}{l}{x+y=100}\\{3x+\frac{1}{3}y=100}\end{array}\right.$ | D. | $\left\{\begin{array}{l}{x+y=100}\\{3x+y=100}\end{array}\right.$ |
3.下列各式计算正确的是( )
0 284054 284062 284068 284072 284078 284080 284084 284090 284092 284098 284104 284108 284110 284114 284120 284122 284128 284132 284134 284138 284140 284144 284146 284148 284149 284150 284152 284153 284154 284156 284158 284162 284164 284168 284170 284174 284180 284182 284188 284192 284194 284198 284204 284210 284212 284218 284222 284224 284230 284234 284240 284248 366461
| A. | a2•a3=a6 | B. | (a2)3=a5 | C. | a2+3a2=4a4 | D. | a4÷a2=a2 |