What are the 9th grade math formulas? What is the summary of math formulas in the first volume of th

The number of the first volume of the ninth grade is summarized as follows:1. Circular dissociation: d>r1+r2, there are 0 intersections; Zheng Na Wai Cut:

d=r1+r2, there is 1 intersection; Shouted and hidden: r1-r2 incision: d=r1-r2, there is 1 intersection; Contains:

0≤d。2. The formula for calculating arc length: l=n r 180.

3. Square difference formula: a2 b2=(a+b)(a-b).

4. Cubic deviation formula: a3- b3=(a-b)(a2+ab+b2).

5、sin(a/2)=√1-cosa)/2)sin(a/2)=-1-cosa)/2)。

Definition A method of solving a one-dimensional quadratic equation for land fissure, also refers to the application of a formula to calculate a transaction.

In addition, there are matching methods, direct opening methods, and factorization methods. Step 1The equation is the general formula ax 2+bx+c=0;

2.Determine the discriminant formula and calculate B2-4AC;

3.If b 2-4ac 0, substitute the formula x=[-b (b 2-4ac)] 2a;

If b 2-4ac<0, the band of the square has no solution in the field of the real stupid number of the deed, and the solution in the field of imaginary numbers is x=[-b (4ac-b 2)] 2a. ] example Solve the equation 2x 2 + 4x-2 = 0.

Solution: x 2 + 2 x - 1 = 0

a=1 b=2 c=-1

b^2-4ac=2^2-4×1×[－1]=4+4=8

Substituting the formula x=[-b (b 2-4ac)] 2a gives x=[-2 8] 2 1=-1 2

x1=-1+√2

x2=-1-√2

Easy to understand method. <>

1. Reaction of zinc and dilute sulfuric acid (hydrogen production in the laboratory): Zn+H2SO4==ZNSO4+H2.

2. Magnesium and dilute hydrochloric acid reaction: mg+2HCl==mgCl2+H2.

3. Hydrogen reduction copper oxide: H2 + Cuo Cu + H2O.

4. Charcoal reduction copper oxide: C+2CuO 2Cu+CO2.

5. Water vapor passes through the calcitrant carbon layer: H2O+C H2+CO.

6. Coke reduced iron oxide: 3C+2Fe2O34Fe+3CO2.

The mathematical formula on the nine: x=(-b b -4ac) 2a

mathematics [English: mathematics, from the ancient Greek máthēma); Often abbreviated as math or maths], it is a discipline that studies concepts such as quantity, structure, change, space, and information.

Mathematics is a general means for human beings to strictly describe and deduce the abstract structure and pattern of things, which can be applied to any problem in the real world, and all mathematical objects are artificially defined in nature. In this sense, mathematics belongs to the formal sciences, not the natural sciences. Different mathematicians and philosophers have a range of opinions on the exact scope and definition of mathematics.

In the historical development and social life of mankind, mathematics plays an irreplaceable role, and it is also an indispensable basic tool for learning and researching modern science and technology.

Algebra is arguably the most widely accepted form of "mathematics". It can be said that since everyone started learning to count when they were young, the first mathematics they came into contact with was algebra. As a discipline that studies "numbers", algebra is also one of the most important components of mathematics.

Geometry was the first branch of mathematics to be studied.

It was not until the Renaissance in the 16th century that Descartes created analytic geometry, linking algebra and geometry, which were completely separate at the time. Since then, we can finally prove the theorems of geometry with calculations; At the same time, it can also be used to visualize abstract algebraic equations and trigonometric functions. Later, calculus was developed into more subtle forms.

The Bourbaki School of France, founded in the thirties of the twentieth century, held that mathematics, at least pure mathematics, is the study of abstract structures. Structuring is a deductive system based on initial concepts and axioms.

According to them, there are three basic parent structures in mathematics: algebraic structures (groups, rings, fields, lattices,......Order structure (partial order, full order,......Topology (neighborhood, limit, connectivity, dimensionality, ,......).