Rules of rational number addition: When adding rational numbers, first judge whether the symbols of two addends are the same sign or different sign, and whether there is 0, so as to determine which rule to use. In the application process, you must remember that "there is a symbol first, then there is an absolute value", so that you will not make mistakes after mastering it. The addition of multiple rational numbers can be calculated from left to right, or by the addition algorithm, but you must think clearly before writing.
Subtraction rule: rational number subtraction rule: subtracting a number is equal to adding the inverse of this number. Among them: two changes: subtraction becomes addition, and subtraction becomes its inverse. Invariant: The minuend is invariant. It can be expressed as: A-B = A+(-B).
Multiplication rule: (1) Multiply two numbers, the same sign is positive, the different sign is negative, and the absolute value is multiplied. Examples; (-5)×(-3)= 15 (-6)×4=-24 (2) Any number multiplied by 0 will get 0. Examples; 0× 1=0 (3) Multiplies several numbers that are not equal to 0, and the sign of the product is determined by the number of negative factors. When the negative factor is odd, the product is negative; When there are even negative factors, the product is positive. Examples; (-10) × [-5 ]× (-0.1)× (-6) = the product is positive, while (-4)×(-7)×(-25)= the product is negative (4). When a factor is 0, the product is zero. 3×(-2)×0=0
Division rule: (1) divided by a number equals to the reciprocal of this number. (Note: 0 has no reciprocal) (2) Divide two numbers, the same sign is positive and the different sign is negative, and divide by the absolute value. (3)0 divided by any number that is not equal to 0 is equal to 0. (4)0 cannot be divided under any conditions.
Algebraic addition and subtraction: Algebraic expression is a part of rational expression, which can include four operations of addition, subtraction, multiplication and division, but in algebraic expression, divisor cannot contain letters. Monomial and polynomial are collectively called algebraic expressions.
Unary linear equations: Equations with only one unknown number are algebraic expressions, and the degree of the unknown number is 1. Such an equation is called a one-dimensional linear equation.
Preliminary understanding of graphics: 1. Points, lines, and surfaces: Through abundant examples, we can further understand points, lines, and surfaces (for example, a city on a traffic map is represented by points, and the picture on the screen is composed of points).
2. Angle
(1) through a wealth of examples, to further understand the angle.
② I will compare angles, estimate the size of an angle, calculate the sum and difference of angles, identify minutes and seconds, and make a simple conversion.
③ Understand the angular bisector and its properties.
I have listed it for you in combination with the contents and concepts in the book. As long as you review and consolidate, I believe you will get good grades. Copying answers is not good for you. I wish you good grades.