The location of the first unit of the sixth grade mathematics knowledge points 1, what is a number pair? Number pair: consists of two numbers, separated by commas and enclosed in parentheses. The numbers in brackets are the number of columns and rows from left to right, that is, "columns first, then rows". Function: Determine the position of a point. Longitude and latitude are the principles. Example: In the grid diagram (plane rectangular coordinate system), it is represented by several pairs (3, 5) (third column, fifth row). Note: (1) In the plane rectangular coordinate system, the coordinates on the X axis represent columns and the coordinates on the Y axis represent rows. For example, the number pair (3, 2) represents the third column and the second row. (2) Logarithm (x, 5) remains unchanged, indicating a horizontal line, and the number of columns (5, y) remains unchanged, indicating a vertical line. (A number is uncertain, so a point cannot be determined) (column, row) Vertical rows are called columns, and horizontal rows are called rows (looking from left to right) (looking from bottom to top) (looking from front to back) 2. The number of lines in the left-right translation of the graph remains unchanged; The number of columns in the chart that move up and down remains the same. 3. The distance between two points has nothing to do with the choice of reference point (0,0). Different reference points lead to different pairs, but the distance between two points remains the same. Unit 2 Fractional multiplication (1) Significance of fractional multiplication: 1. The meaning of fractional multiplication by integer is the same as that of integer multiplication, which is a simple operation to find the sum of several identical addends. Note: "Fraction times integer" means that the second factor must be an integer, not a fraction. For example, ×7 means: What is the sum of seven? How much is seven times? 2. Multiplying a number by a fraction means finding the fraction of a number. Note: "A number multiplied by a fraction" means that the second factor must be a fraction, not an integer. The first factor can be anything. For example, × means: What is it? 9× means: What is the number of 9? A× means: What's the number of A? (2) Calculation rule of fractional multiplication: 1. The calculation rule of fractional multiplication by integer is: numerator multiplied by integer, denominator unchanged. Note: (1) In order to simplify the calculation, the score can be reduced first and then calculated. (integer and denominator divisor) (2) divisor is to subtract the greatest common factor from the following integer and denominator. (Integer cannot be multiplied by denominator, and the calculation result must be the simplest fraction) 2. The arithmetic of fractional multiplication is: use the product of molecular multiplication as numerator and the product of denominator multiplication as denominator. (Molecule times numerator, denominator times denominator) Note: (1) If the fractional multiplication formula contains a fraction, it should be converted into a false fraction before calculation. (2) The method of fractional simplification is to divide the numerator and denominator by their greatest common factor at the same time. (3) In the process of multiplication, the divisor is to cross out two divisible numbers in the numerator and denominator, and then write the divisor above and below respectively. (After division, the numerator and denominator must not contain common factors, so the calculated result is the simplest fraction. (4) The basic nature of the fraction: the numerator and denominator are multiplied or divided by the same number at the same time (except 0), and the size of the fraction remains unchanged. (3) Relationship between product and factor: a number (except 0) multiplied by a number greater than 1, and the product is greater than this number. A×b=c, when b >; At 1, the product of a number (except 0) multiplied by a number less than 1 in c>a is less than this number. A×b=c, when b