What are the formulas and theorems in junior high school mathematics,

What are the formulas and theorems in junior high school mathematics,

Junior high school mathematics books have ah, if there is no book, you can find according to the knowledge point

Is the formula MGH = MV ^ / 2 + Q suitable for high school physics electromagnetic induction?

Of course not. This formula is actually energy conservation. Gravitational potential energy is converted into kinetic energy and internal energy. It is applicable to a conductor falling freely from the magnetic field. However, if the conductor is pulled horizontally with constant force into the magnetic field, there will be no change in gravitational potential energy

If the side length of a large square is 2, find the area of four ellipses in the square

The answer is 2 π - 4
It is equivalent to cutting a square into four small squares
In each small square, make two quarter arcs with two diagonals to form an ellipse with the diagonal of the square as the major axis
Then calculate the area of each ellipse, and finally multiply by 4

Example: she, gentle, lamb
She's as gentle as a lamb.
1.(He,fast,horse)
2.(Tom,strong,ox)
3.(He,brave,lion)

He's as fast as a horse.
Tom's as strong as an ox.
He's brave as a lion.

If the polynomial 2x2-3x + k-kx2 + 4kx-4 is a quadratic binomial without constant term, then the quadratic binomial is______ ．

The second binomial is - 2x2 + 13X, so the answer is - 2x2 + 13X

No matter what the value of P is, does the equation (x-3) (X-2) - P2 = 0 always have two unequal real roots?

(x-3) (X-2) - P2 = 0x & # 178; - 2x-3x + 6-P & # 178; = 0x & # 178; - 5x + 6-P & # 178; = 0 ⊿ = (- 5) &# 178; - 4 × 1 × (6-P & # 178;) = 25-24 + 4P & # 178; = 4P & # 178; + 1 ≥ 1  whatever the value of P, the equation (x-3) (X-2) - P2 = 0 always has two unequal real roots

Several simple calculation and application problems
3 / 10x8 = 6x7 / 2 = 2x12 / 3 = 24x8 / 3 = 8x4 / 9 = 1x3 / 2 = 5x20x19 / 3 = 5x5 / 16 / 4 / 40 / 13x39 / 5 = 1 kg of lactose in one kilogram of milk, The content of protein is 7.1kg of lactose. How many kilos of protein does milk contain? (this is an application question) 15 divided by 5 of 13 = 9 divided by 5 of 3 = 7 divided by 14 of 15 = 12 divided by 7 of 8 = 3 divided by 6 of 11 = 36 divided by 7 = 3 divided by 2 = 7 of 7 = help, uncles

10×（3／8）＝（10×3）／8＝30／8＝15／46×（2／7）＝（6×2）／7＝12／7（2／3）×12＝（2×12）／3＝24／3＝824×（3／8）＝（24×3）／8＝72／8＝9（8／9）×（3／4）＝（8×3）／（9×4）＝24／36＝2／3（1／...

Given that the function f (x) = KX ^ 3 + 3 (k-1) x ^ 2-k ^ 2 + 1 (k > 0) is a decreasing function on (0,4), the value range of real number k is obtained
The answer is probably to find X1 and X2 after derivation, and then use Weida's theorem X1 + x2 > 4 to solve it
My question 1: can we discuss the size of x1.x2 after finding X1 and X2, and use x24 when x1x2?
My question 2: when can we use this method to solve the problem? In case what (2,4) instead of (0,4) can we use this method to solve this problem?

Problem 1, yes, problem 2, this problem is very special. The root of derivative function has been determined to be zero, so as long as there is k, we can use Weida's theorem, which is equivalent to another root greater than or equal to the maximum value of interval. By the way, all the above should be greater than or equal to

As shown in the figure, in the straight triangular prism a1b1c1-abc, ∠ BAC = π 2, ab = AC = A1A = 1, it is known that G and E are the middle points of edges A1B1 and CC1 respectively, and D and F are the moving points (excluding the end points) on line segments AC and AB respectively. If GD ⊥ EF, then the length range of line segment DF is ()
A. [15，1）B. [15，2）C. [1，2）D. [15，2）

Establish the space rectangular coordinate system as shown in the figure, then a (0, 0, 0), e (0, 1, 12), G (12, 0, 1), f (x, 0, 0), D (0, y, 0) due to GD ⊥ EF, so & nbsp; & nbsp; X + 2y-1 = 0df = x2 + y2 = 5y2 − 4Y + 1 = 5 (Y − 25) 2 + 15 ∵ 0 & lt; X & lt; 1, 0 & lt; Y & lt; 1, ∵ 0 & lt; Y & lt; 12. When y = 25, the minimum value of DF length of line segment is 15. When y = 0, the maximum value of DF length of line segment is 1, not including the end point, so y = 0 cannot be taken as 1, so a

PV = NRT launch PV = (M / M) rt launch PM = (M / V) rt launch PM = P (density) RT. what do R, t and t stand for?

PV = NRT deduces PV = (M / M) rt deduces PM = (M / V) rt deduces PM = P (density) RT. R is the proportion coefficient (constant), t is the absolute temperature (Kelvin), t is the temperature (centigrade)