当 a = 33 时计算 a – 13

代数是数学的一个分支，我们在其中研究数字、变量以及算术运算运算符。代数的主要用途是寻找未知数。没有常数值的项称为未知项，由字母或符号表示。假设字母的值可以根据对其应用的操作而变化，因此我们也将其称为变量。具有恒定值的项称为数字，并用数字表示。

算术表达式

An arithmetic expression is the representation of the mathematical statement into the mathematical expression with the help of numerals, variables, and arithmetic operators. For example: ‘Four times a number added to 6’ can be written as ‘4x+6’. Here we don’t know the unknowns so we represent them by ‘x’. 

在上面的表达式“4x+6”中，加号将表达式分成两个项。因此，根据术语的数量，表达式可以分为以下类型。

• 单项式：如果表达式中的项数为 1，则称为单项式。示例：6x、8t 等。
• 二项式：如果表达式中的项数为两个，则称为二项式。示例：3t+2、8r-6 等。
• 三项式：如果表达式中的项数为三，则称为三项式。示例：5a-6c+3b、8r+5d+3s 等。
• 多项式：如果表达式中的项数为一项或多于一项，则该表达式称为多项式。

表达的价值/评价

As we have discussed that algebraic expression is the combination of numerals and variables. Variable can take any value in the expression according to the condition given. But if it has already been given then we don’t have the option to choose any other value. Put the value of variables in the given expression, that will be the evaluation of the expression.

解决问题的步骤：

Step 1: Put the value of the variable in the given expression.

Step 2: Do the calculation according to the arithmetic operators. 

Step 3: Simplify to the lowest term to get the answer.

当 a = 33 时计算 a – 13

解决方案：

Given Expression = a – 13

We have to find the value of the expression at a = 33.

Put a = 33 in the expression.

= 33 – 13

Solve the expression according to the operators.

= 20

So the evaluation of the expression (a-13) at a = 33 is 20.

类似问题

问题 1：当 x = 36 时，x – 22 的评估是什么？

解决方案：

Given Expression = x-22

We have to find the value of the expression at x = 36.

Put x=36 in the expression.

= 36 – 22

Solve the expression.

= 14

So the evaluation of x – 22 at x = 36 is 14.

问题 2：当 y = -6 时，y – 14 的评估是什么？

解决方案：

Given expression = y – 14

We have to find the value of the expression at y = -6

Put y = -6 in the given expression.

= -6-14

Solve the expression according to the arithmetic operator.

= -20

So the evaluation of y-14 at y=-6 is -20.