Basic knowledge of algebra 1. Algebraic formula: the formula that uses the operation symbol "+-××……" to express the relationship between letters and numbers is called algebraic formula (the number obtained by letters should ensure that the formula in which it belongs is meaningful, and the number obtained by letters should also make real life or production meaningful; A single number or letter is also algebraic)
2. Some points for attention in column algebra:
(1) number multiplied by letters, or letters multiplied by letters are usually multiplied by "",or writing is omitted;
(2) When multiplying numbers, you should still use "x" instead of "",and you can't omit the multiplication sign;
(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 two numbers as A and B respectively, we should classify them and write them as a-b and B-A. 。
3. Several important algebraic expressions: (m and n represent integers)
(1) The square difference between A and B is: A2-B2; The square of the difference between a and b is: (a-b) 2;
(2) If a, b and c are positive integers, the two-digit integer is 10a+b and the three-digit integer is10a+10b+c;
(3) If both m and n are integers, the quotient m is divided by 5, and the remainder n is 5m+n; Even number is 2n, and odd number is 2n+1; Three consecutive integers are: n- 1, n, n+1;
(4) If b>0, positive number is: a2+b, negative number is: -a2-b, non-negative number is: a2, and non-positive number is: -a2.
The odd power of rational number negative number is negative number; Even the power of negative numbers is positive; Note: When n is positive odd number: (-a)n=-an or (a-b)n=-(b-a)n, when n is positive even number: (-a)n=an or (a-b) n = (b-a) n. 。
One-dimensional linear equation 1 One-dimensional linear equation: an integral equation with only one unknown number, whose degree is 1 and whose coefficient is not zero.
2. The standard form of one-dimensional linear equation: ax+b=0(x is unknown, a and b are known numbers, a≠0).
3. Conditions: A linear equation with one variable must meet four conditions at the same time:
(1) It is an equation;
(2) There are no unknowns in the denominator;
(3) The highest unknown term is1;
(4) The coefficient of the term with unknown number is not 0.
The above is a summary of the seventh grade mathematics knowledge points I have compiled for you, hoping to help you. For more information about the senior high school entrance examination, you can continue to pay attention to this site!