Related concepts of real number 1 and reciprocal
Algebraic meaning of (1): There are only two numbers with different signs, and we say that one of them is opposite to the other. The antonym of 0 is 0.
(2) Geometric meaning: On both sides of the origin on the number axis, two points with the same distance from the origin represent two opposite numbers, or on the number axis, the points corresponding to two opposite numbers are symmetrical about the origin.
(3) The sum of two opposites is equal to 0.a and B are opposites a+b=0.
2. Absolute value | a | ≥ 0.
Step 3 count down the seconds
(1)0 has no reciprocal.
(2) Two numbers whose product is 1 are reciprocal.
4. Square root
(1) If the square of a number is equal to a, this number is called the square root of a, a positive number has two square roots, and the two square roots are in opposite directions; 0 has a square root, and the square root itself is 0; Negative numbers have no square root.
(2) The positive square root of a positive number is called the arithmetic square root of a. ..
5. Cubic root
If x3=a, then x is called the cube root of a, and positive numbers have positive cube roots; Negative numbers have negative cubic roots; The cube root of zero is zero.
The intersecting lines have equal vertex angles.
One and only one straight line is perpendicular to the known straight line.
Of all the line segments connecting points outside the straight line and points on the straight line, the vertical line segment is the shortest.
The parallel line 1 passes through a point outside the straight line, and one and only one straight line is parallel to this straight line.
2. If two straight lines are parallel to the third straight line, then the two straight lines are also parallel to each other.
3. Conditions of parallel lines:
4. Two straight lines are cut by the third straight line. If congruent angles are equal, two straight lines are parallel and cut by a third straight line. If the offset angles are equal, two straight lines are parallel (offset angles are equal, two straight lines are parallel).
5. Two straight lines are cut by the third straight line. If they are complementary to the inside corner, then two straight lines are parallel (complementary to the inside corner, two straight lines are parallel).
The property of parallel lines is 1. Two parallel lines are cut by a third line, and the juxtaposition angles are equal (the two lines are parallel and the juxtaposition angles are equal).
2. Two parallel lines are cut by the third line, and the internal dislocation angles are equal (the two lines are parallel and the internal dislocation angles are equal).
3. The two parallel lines are cut by the third straight line, which are complementary to the lateral inner angle (the two straight lines are parallel and complementary to the lateral inner angle). The sentence that judges a thing is called a proposition (this test site may appear in the rewriting of the proposition in the fill-in-the-blank question and in the multiple-choice question to judge whether the proposition is true or false).
Inequality 1, a formula that indicates the relationship between size with less than sign or greater than sign, is called inequality.
2. The value of the unknown quantity that makes the inequality valid is called the solution of the inequality.
3. The range of value of x that can make inequality hold is called the solution set of inequality, or simply the solution set.
4. An inequality with an unknown degree of 1 is called one-dimensional linear inequality.
5, the essence of inequality:
Add (or subtract) the same number (or formula) on both sides of the inequality, and the direction of the inequality remains unchanged.
Both sides of inequality multiply (or divide) the same positive number, and the direction of inequality remains unchanged.
When both sides of the inequality are multiplied (or divided) by the same negative number, the direction of the inequality changes.
The difference between any two sides in a triangle is less than the third side.
The sum of any two sides in a triangle is greater than the third side.
The above are the knowledge points of mathematics in Book 2 of Grade 1, I hope I can help you.