What are the inductions of mathematical formulas from the first to the third year of junior high sch

Rational numbers – comparison: a=0, |a|=0 a>0,|a|=a a<0,|a|=-a

a|>|b|, a<0, b<0, then a additive commutative law: a+b=b+a

Additive associative law: (a+b)+c=a+(b+c)Subtraction law: a-b=a+(-b).

Commutative law of multiplication: ab=ba

Multiplicative associative property: (ab)c=a(bc).

Division: a b=a(1 b)【b≠0】

Angles and lines – equal to the top angles.

Within the same plane, there is one and only one line perpendicular to a known line.

In the same plane, passing a point outside the line, there is one and only one line parallel to the known line.

If both lines are parallel to the third line, then the two lines are also parallel to each other.

Two lines perpendicular to the same line are parallel to each other.

The isotope angle is equal The internal misalignment angle is equal The same side internal angle is complementary: two straight lines are parallel.

The two straight lines are parallel: the isotopic angles are equal, the internal misalignment angles are equal, and the contemporal internal angles are complementary.

Right angle = 90°, 180° "Superior angle< 360°, flat angle = 180°, circumferential angle = 360°

90° "obtuse angle< 180°, 0° "acute angle< 90°

The first volume of junior high school] rational numbers - comparison: a=0, |a|=0 a>0,|a|=a a<0,|a|=-a

a|>|b|, a<0, b<0, then ab, then a+c>b+c, a-c>b-c

If A>B, C>0, then AC>BC

If a>b, c<0, then ac0).

The sum of the outer angles of the polygon: 180°

The sum of the inner angles of the polygon: 180°*(n-2).

Number of sides of the polygon: n sides.

Number of diagonal lines: n(n-3) 2

The interior angles of a regular polygon: 180°-360° N

Mathematical formulas from the first to the third year of junior high school:1. Square difference formula.

a²-b²=(a+b)(a-b)。

2. Perfect square formula.

a²+2ab+b²=(a+b)²。

3. Cube sum formula: a +b = (a + b) (a -ab + b).

4. Cubic variance formula.

Songwanshan a -b Nonaka = (a-b) (a +ab + b).

5. Complete cube sum formula.

a³+3a²b+3ab²+b³=(a+b)³。

6. The formula of complete cubic variance: a -3a b + 3ab -b = (a-b).

7. Three perfect square formulas: a + b cheat + c + 2ab + 2bc + 2ac = (a + b + c).

8. The formula for the sum of the cubes of the three terms: a + b + c -3abc = (a + b + c) (a + b + c -ab-bc-ac).