Rational number rule 1, rational number addition rule: add two numbers with the same symbol, take the same symbol, and add the absolute values; Two numbers with different signs are added, and the sum is 0 when the absolute values are equal; When the absolute values are not equal, take the sign of the number with larger absolute value and subtract the number with smaller absolute value from the number with larger absolute value; Add a number to 0 and you still get the number. It can be concluded that the sum of two opposite numbers is 0; Add three numbers to add the first two numbers, or add the last two numbers first, and the total remains the same.
2. the subtraction rule of rational numbers: subtracting a number is equal to adding the reciprocal of this number. Note: All addition and subtraction operations can be unified as addition operations.
3. Multiplication rule of rational numbers: two numbers are multiplied, the same sign is positive, the different sign is negative, and the absolute value is multiplied. Any number multiplied by zero equals zero.
4. Division rule of rational numbers: divide two numbers, the same sign is positive, the different sign is negative, and divide by the absolute value. Divide zero by any number that is not zero to get zero.
The first step of solving the one-dimensional linear equation: remove the denominator, multiply both sides of the equation by the least common multiple of each denominator, be careful not to omit the term without denominator, and put brackets around the numerator if it is polynomial;
(2) Open the brackets, usually first open the brackets, then open the brackets, and finally open the braces. Be careful not to omit the items in brackets. When the "-"is in front of the brackets, pay attention to the symbols of the items in brackets when removing the brackets;
③ Shift the term, that is, move the term with unknown number to one side of the equation, and move the term without unknown number to the other side of the equation. Pay attention to the sign change of the shift term, and the shift term and the exchange position are different;
(4) merging similar terms, i.e. merging similar terms into one term, transforming the equation into the form of ax=b(a≠0), and paying attention to merging only the coefficients of similar terms;
⑤ Transform the coefficient into 1 and divide it by A on both sides of equation ax=b to find the solution of equation x=. Pay attention to symbols, and don't write the solution of equation ax=b as x=.
Under the condition of parallel lines, two lines are cut by a third line. On the same side of two cutting lines, on the same side of the cutting line, such two angles are called congruent angles.
Two straight lines are cut by a third straight line, and between the two cutting lines, on both sides of the cutting line, such two angles are called inscribed angles.
Two straight lines are cut by a third line, and between the two cut lines, on the same side of the cut line, such two angles are called ipsilateral internal angles.
Judgment method of two parallel lines:
Method 1 Two straight lines were cut by the third straight line. If congruent angles are equal, two straight lines are parallel. To put it simply: the same angle is equal and two straight lines are parallel.
Method 2 Two straight lines are cut by a third straight line. If the internal dislocation angles are equal, two straight lines are parallel. To put it simply: the internal dislocation angles are equal and the two straight lines are parallel.
Method 3 Two straight lines are cut by a third straight line. If they are complementary, then these two straight lines are parallel. To put it simply: the internal angles on the same side are complementary and the two straight lines are parallel.
The above is the key content of the notes I gave you on math study in Grade One of Senior High School, which is for reference only and I hope it will help you.