Rational numbers add and subtract 1, two numbers are added with the same sign, take the same sign, and the absolute values are added. Add two different symbols with different absolute values, take the symbol with the larger absolute value, and subtract the symbol with the smaller absolute value from the larger absolute value.
2. Two opposite numbers add up to get 0.
When a number is added to 0, you still get this number.
Subtracting a number is equal to adding the reciprocal of this number.
Power 1, power definition: the operation of finding the product of n same factors is called power.
2. The base is a, the exponent is n, and the power is the result of power; Read: n power of or n power of.
3. The odd power of a negative number is negative, and the even power of a negative number is positive. Any power of a positive number is a positive number, and any power of a positive integer is 0.
One-dimensional linear equation 1, and equations with unknown numbers are called equations.
2, only contains an unknown (yuan), the unknown index is 1 (times), such an equation is called a linear equation. ?
3. It is a method to solve practical problems by analyzing the quantitative relations in practical problems and listing equations by using their equal relations. ? Solving the equation is to find the value of the unknown quantity that makes the left and right sides of the equation equal, and this value is the solution of the equation. ?
What are the properties of the equation? Properties of equation 1: Add (or subtract) the same number (or formula) on both sides of the equation, and the results are still equal.
Property 2 of the equation: Multiply both sides of the equation by the same number, or divide by the same number that is not 0, and the results are still equal.
Angle comparison? 1, starting from the vertex of an angle, the ray that divides this angle into two equal angles is called the bisector of this angle. Similarly, there is the so-called bisector.
2. Complementary angle and complementary angle
(1) If the sum of two angles is equal to 90 (right angle), the two angles are said to be complementary to each other. ?
(2) If the sum of two angles is equal to 180 (flat angle), the two angles are said to be complementary. ?
(3) The complementary angles of equal angles are equal. ? Equiangular complementary angles are equal.
Parallel line 1, in the same plane, if there is no intersection point, two straight lines are parallel to each other, which is recorded as: a∨b?
2. There are only two relationships between two straight lines in the same plane: intersecting or parallel. ?
3. Parallelism axiom: After passing a point outside a straight line, there is one and only one straight line parallel to this straight line. ?
If two straight lines are parallel to the third straight line, then the two straight lines are also parallel to each other.
The above are the key points of junior one mathematics that I sorted out. I hope it will help you.