Algebraic expression 1 Algebraic expression: the expression of the number of connections, and the letter that represents the number with the operation symbol "+-×××" is called algebraic expression (the number obtained by the letter should ensure that the formula in which it is located is meaningful, and the number obtained by the letter should also make the actual life or production meaningful; A single number or letter is also algebraic)
2. Some points for attention in column algebra:
Multiply (1) by letters, or multiply letters by letters, or omit;
(2) When the numbers are multiplied, they should still be multiplied by "×", but not by "×", and the multiplication sign cannot be omitted;
(3) When a number is multiplied by a letter, the number is usually written in front of the letter in the result. For example, a×5 should be written as 5a;
(4) When the band fraction is multiplied by letters, the band fraction should be changed to a false fraction, for example, a× should be written as a;
(5) When there is a division operation in the algebraic expression, the division method and the division method are generally connected by a fractional line, such as the form written in 3 A;
(6) The difference between A and B should be written in alphabetical order; If we only talk about the difference between two numbers, when we set the two numbers as A and B respectively, we should classify them and write them as a-b and B-A. ..
Intersection line 1, definition: two straight lines intersect, and one of the four angles formed is a right angle, then the two straight lines are perpendicular to each other. One of the straight lines is called the perpendicular of the other straight line, and their intersection point is called the vertical foot.
2. Note:
(1) The vertical line is a straight line.
The four angles formed by two vertical lines are all 90.
(3) Verticality is a special case of intersection.
(4) Vertical symbols: a⊥b, AB⊥CD.
3. Draw a known straight line with countless vertical lines.
4. There is one and only one straight line perpendicular to the known straight line.
5. Of all the line segments connecting points outside the straight line and points on the straight line, the vertical line segment is the shortest. Simply put: the vertical line is the shortest.
6. The length from a point outside a straight line to the vertical section of the straight line is called the distance from the point to the straight line.
7. One vertex has a common * * *, one side has a common * * *, and the other side is an extension line opposite to each other. Such two angles are called adjacent complementary angles.
There are four pairs of adjacent complementary angles when two straight lines intersect.
8. One vertex has a common * * *, and both sides of the corner are opposite extension lines. These two angles are called antipodal angles. Two straight lines intersect and have two opposite angles. The vertex angles are equal.
Algebraic expression 1 algebraic expression: Algebraic expression is a general term for monomial and polynomial, and it is a part of rational formula. In rational expressions, there can be five operations: addition, subtraction, multiplication, division and multiplication, but in algebraic expressions, the divisor cannot contain letters.
2. Monomial: An algebraic expression composed of the product of numbers or letters is called a monomial, and a single number or letter is also called a monomial.
3. Polynomials: Algebraic expressions composed of several monomials are called polynomials.
4. Coefficient: The sum of the indices of all the letters in the monomial is called its number.
5. Times: The sum of the indexes of all variables in a single item is called the times of this single item.
6. Term: Each monomial that constitutes a polynomial is called a polynomial term.
7. Constant term: In polynomials, each term without letters is called a constant term.
8. Degree of Polynomial: In a polynomial, the degree of the term with the highest degree is called the degree of this polynomial.
9. Similar terms: In polynomials, terms with the same letters and the same index of the same letters are called similar terms.
10. Merging similar items: Merging similar items in polynomials into one item is called merging similar items.