Before doing these questions, let's briefly review the concept of algebra.

Review the concept of algebra. As we all know, concept is the only criterion. In other words, judging whether a formula is algebraic depends on whether each element in the formula conforms to the concept of algebraic expression. If it meets the requirements of the algebraic concept, it is algebraic, and if it does not meet the algebraic concept at all, it is not algebraic.

The concept of algebra has already told us the standard to judge whether it is algebra or not and what it looks like. Only when you look at the algebraic expression clearly will you see the tricky problem in the topic and will not fall into the pit.

Before doing these eight questions, let's simply restore the algebraic expression.

Through the systematic explanation of the concept of algebra yesterday, we all know that the concept of algebra emphasizes three key points, namely numbers, letters and operational symbols.

In other words, algebraic expressions are composed of these three key points alone or together. For example, a single number, a single letter, numbers connected by operation symbols, letters connected by operation symbols, numbers and letters connected by operation symbols are all algebraic expressions.

Whether alone or together, as long as it is algebra, it can't run out of the scope of these three key points. Once other types of mathematical elements appear, they are not algebraic.

The figures are easy for us to understand. They are nothing more than integers, fractions and decimals, not to mention letters. Let's focus on the operation symbols.

So what are the commonly used operation symbols in junior high school?

Obviously, there are plus sign (+), minus sign (-), multiplication sign (X), division sign (), comparison sign (:), fractional line (-), root sign (√ ~), power and logarithm to be learned in senior high school. ...

What needs to be noted here is that there is another big class of symbols in mathematics, that is, relational symbols.

The relational symbol is not an operational symbol, and the operational symbol is not equal to the relational symbol. They are two completely different categories and must be distinguished.

So, what are our common relational symbols?

There is a greater than sign (>) and a less than sign (

At this point, we have seen three key points in the concept of algebra more clearly, and I believe it will be more handy to start these eight topics.

With the algebraic concept of solving problems, we began to do the problem:

1、t/x-ab+88

Because t, x, a and b are letters, which conform to the concept of algebra; 88 is a number, which conforms to the concept of algebra; /,-and+are operational symbols, which conform to the concept of algebra. In other words, every part of this formula conforms to the algebraic concept.

So "t/x-ab+88" is an algebraic expression.

2、7/x+33= 188

Because x is a letter, it conforms to the algebraic concept; 33, 188 is a number, which conforms to the algebraic concept; /and+are operation symbols, which conform to the concept of algebra. However, "=" is not an operational symbol, but a relational symbol, which does not conform to the algebraic concept. In other words, this formula is somewhat inconsistent with the concept of algebra.

So "7/x+33= 188" is not algebraic.

3、a≥b

Because a and b are letters, they conform to the concept of algebra; But "≥" is not an operational symbol, but a relational symbol, which does not conform to the algebraic concept. In other words, this formula is somewhat inconsistent with the concept of algebra.

So "a≥b" is not algebraic.

4. A: B: C

Because a, b and c are letters, which conform to the concept of algebra; ":"is an operation symbol, which conforms to the concept of algebra. In other words, every part of this formula conforms to the algebraic concept.

So "a:b:c" is algebraic.

5、3+8= 1 1

Because 3,8, 1 1 is a number, it conforms to the algebraic concept; However, "=" is not an operational symbol, but a relational symbol, which does not conform to the algebraic concept. In other words, this formula is somewhat inconsistent with the concept of algebra.

So "3+8= 1 1" is not an algebraic expression.

6、√ 16+4

Because 16 and 4 are numbers, they conform to the algebraic concept; "√ ~" and "+"are operation symbols, which conform to the algebraic concept. In other words, every part of this formula conforms to the algebraic concept.

Therefore, "√ 16+4" is an algebraic expression.

7、8? -6

Because 8 and 6 are numbers, they conform to the concept of algebra; The power sum "-"is an operation symbol, which conforms to the algebraic concept. In other words, every part of this formula conforms to the algebraic concept.

So, "8? -6 "is algebra.

8、a≈ 168

Because 168 is a number, it conforms to the algebraic concept; But "≈" is not an operational symbol, but a relational symbol, which does not conform to the algebraic concept. In other words, this formula is somewhat inconsistent with the concept of algebra.

So "a≈ 168" is not algebraic.

The final result is as follows:

Through these eight typical judgment questions about algebra, we can easily find that even the most difficult questions are easy to do as long as we thoroughly understand the mathematical concepts, grasp the essence of the concepts and understand the key points in the concepts, right?

Briefly summarize the questions, let's make a summary together:

1, algebraic expression is not an equation;

2. Symbols in algebraic expressions can only be operational symbols, and no other symbols can appear;

3. A formula is not algebraic as long as it does not conform to the concept of algebra at all.

At the end of the homework, write a formula for everyone to see if this formula is algebraic:

|x-7|+ab (that is, the absolute value of x-7 +ab)

Interested friends, you can write your answer in the comment area, and I will publish the correct answer in the comment area. Of course, what other typical topics can be put in the comment area? ......