The proof of dy / DX f（x）＝cos x＋sin x／cos x－sin x It is proved that f '(x) = 2 / 1-sin 2x . .

The proof of dy / DX f（x）＝cos x＋sin x／cos x－sin x It is proved that f '(x) = 2 / 1-sin 2x . .

The derivative formula of quotient is used to calculate directly, and trigonometric function knowledge is used to simplify

How many kilometers is one meter
one thousand two hundred and fifty-four

1km=1000m
1m=0.001km

x＝e^t (COS t) y＝e^t Sin t
When DX / DT,
How to get e ^ t (- Sint) + e ^ t (cost)
When dy / DT,
How to get e ^ t (cos t) + sin t (e ^ t)
Please refer to B (II) of question 7 on page 28 for details

DX / dt = x '(T) = (e ^ t)' * (cost) + (e ^ t) * (cost) '= (e ^ t) * (cost) + (e ^ t) * (- Sint) similarly, y = e ^ t (sin T) dy / DT is the derivation of the above formula to t: dy / dt = y' (T) = (e ^ t) '* (sin T) + (e ^ t)

How many kilometers is one meter?

One kilometer is equal to one kilometer (1km = 1000m). Therefore, one meter is equal to 0.001 kilometer

How to find dy ^ 5 / DX derivative?
This is a derivative of X

Let f (y) = y ∧ 5, then dy ∧ 5 / DX = DF (y) / DX = f '(y) * y' = 5Y ∧ 4 * y 'solution 2: dy ∧ 5 / DX = dy ∧ 5 / dy ∧ dy / DX = 5Y ∧ 4 * y' hint: in Dy ∧ 5 / DX, y ∧ 5 is a composite function! By y = y (x) and f (y) = y ∧ 5 complex function

How to convert the 7000 yuan per ton of hot-dip galvanized steel pipe DN 150 into the price per meter? What is the conversion formula?

You have to know how many meters a ton is. Of course, you can also calculate by yourself. For example, if the outer diameter of the steel coil D and the wall thickness h, the weight of 1 meter strip is 7850 * 3.14 * {(D / 2) & sup2; - (D / 2-h) & sup2;} * 1 D / h is converted into meters, and the unit of the result is kg. You can know how much the weight of 1 meter is

Dy / DX = tany, find the analytic expression of Y

By transforming the t power of u = tany, x = e, we try to change the equation x ^ 2D ^ 2Y / DX ^ 2 + 2x ^ 2 (tany) (dy / DX) ^ 2 + XDY / DX sinycosy = 0 to the equation u = tany, x = e ^ t.du = (SecY) ^ 2dy = [1 + (tany) ^ 2] dy = (1 + u ^ 2) dy, Dy = Du / (1 + u ^ 2), DX = E^ tdt.dy/dx=1/ [e^t(1+u^2)]du/dt...

What are some commonly used unit conversion? For example, 1A =? Ma, 1L =? Ml, etc. ~ to be commonly used. I review~
I don't want the examples I give ~ I want all the common ones~

These
1A=100mA 1L=1000 mL 1kg=1000g=1000 000mg
1m=10dm=100cm=1000mm 1km=1000m
1Pa=1N/m^2 1 m^2=100 dm^2=10000 cm^2
1m/s=3.6km/h
1m^3=1000dm^3=1000 000cm^2
1kg/m^3=1000g/cm^3
Wait for conversion. In fact, you just need to remember it. It's not hard to memorize
What's important about physics in senior high school entrance examination
1. Back formula such as P = f / S
2. Some important concepts
3. Do more exercises, especially calculation
4. Look at some small knowledge points, such as the name of a scientist. These multiple-choice questions are easy to test. For example, Newton proposed Newton's first law and so on
Don't spend too much time on unit conversion

Derived from (DX) / (Dy) = 1 / y ': (d ^ 2x) / (Dy ^ 2) = - y' '/ (y') ^ 3
rt
In addition, what does "d" mean here? Tongji 6 p.90 suddenly comes out with the derivative function expressed by D, and the concept of "d" has not been explicitly put forward
What about (d ^ 3) x / D (y ^ 3)

In this paper, we find that the derivation function is the result of the following: the derivation function is the result of the differential. D [(DX) / (DX) / (Dy) / (Dy \35\\\\\\\\\35\\\\\\\\\\\\\\\; 178; 178; 178; (\\\\\\\\\\\\\\\\\\\y ') & _

It should be specific and practical
Such as conversion between cubic meters and cubic centimeters

1 m3 = 1000 cubic decimeter = 1000000 cubic millimeter
1 square meter = 100 square decimeter = 10000 square centimeter
1 m / S = 3.6 km / h
1kW / h = 3600000 joules