1.A quantity which has a fixed numerical value is called a constant.
2.A quantity which can take various numerical values is called a variable.
3.An algebraic expression is a combinaation of constants and variables.
1.A quantity which has a fixed numerical value is called a constant. 一个已经有了既定数值的数量，称之为常数（常量）。 2.A quantity which can take various numerical values is called a variable. 一个可以取不同数值的数量，称之为变数（变量）。 3.An algebraic expression is a combination of constants and variables. 代数式即，常数与变数这两者的组合。...
