X power of Z = y + 1 power of 8, y power of 9 = X-8 power of 3, find xy =?

X power of Z = y + 1 power of 8, y power of 9 = X-8 power of 3, find xy =?

∵ x power of Z = y + 1 power of 8 = (2 ^ 3) ^ (y + 1) = 2 ^ (3Y + 3)
∴x=3y+3①
∵ 9 to the power of y = 3 to the power of X-8, 9 ^ y = 3 ^ (2Y)
∴2y=x-8②
① Substituting into 2, 2Y = 3Y + 3-8
∴y=5
Substituting ①, x = 18
∴xy=18*5=90

Z = f (x * X-Y * y, XY power of E) for Z to x partial derivation and Z to y partial derivation

Let v = x * X-Y * y, u = exp {XY} then DV / DX = 2x (here we should use the partial derivative sign instead), DV / dy = 2Y, Du / DX = y * exp {XY}, Du / dy = x * exp {XY}, then DZ / DX = DZ / DV * DV / DX + DZ / Du * Du / DX = 2x * DZ / DV + y * exp {XY} * DZ / dudz / dy = DZ / DV * DV / dy + D

Calculus, how to find the inner normal vector of a curve, the original problem is as follows

Let the equation of plane curve be a parameter equation, x = x (T), y = y (T), then the tangent vector at the point (x, y) corresponding to the parameter t is (x '(T), y' (T)), and the vector perpendicular to it is a normal vector, one of which can be recorded as (y '(T), - x' (T))
If the equation of the curve is y = f (x), the parameter equation can be regarded as x = x, y = f (x), so one of the normal vectors is (y ', - 1)
－－－
For this problem, we can find y '= - B / A, so the normal vector is (- B / A, - 1). The inner normal vector refers to the vector pointing inward from the tangent, so the angle between it and the positive direction of X axis is greater than or equal to 90 °, so the x component should be negative or 0, so (- B / A, - 1) is the result

Yucai Middle School 600 teachers and students go out to visit the exhibition of science and Technology Museum. The school is going to go there by car. It is known that a bus carries 20 more people than a van, and six buses are bigger
If all the teachers and students take minibuses, how many do the schools need to rent? How many do they take buses

12

Finding the limit Lim x tends to 0 [e ^ (tanx-x) - 1] / (tanx-x)
Ask the great God not to use romeda and use romeda respectively. Thank you

Tanx-x tends to zero when x tends to zero
If we regard tanx-x as t, e ^ (tanx-x) - 1 = e ^ (T) - 1 = t
If the denominator is also t, then the answer is 1
In the words of Robita's law, it is necessary to seek the upper and lower derivatives
The molecule is equal to e ^ (tanx-x) (SEC ^ x-1)
The denominator is equal to (SEC ^ x-1) and the upper and lower approximations (SEC ^ x-1) are equal to e ^ (tanx-x). Is this limit 1
All the answers are the same

In the sequence an, A1 = 1, an * a (n + 1) = the nth power of 4, s2n =?

a(n+1)=4^n/an=4^n/(4^(n-1)/a(n-1))=4a(n-1)
a1=1
a2=4/a1=4
a3=4a1=4
a4=4a2=4^2
……
a(2n-1)=4^n-1
a(2n)=4^n
s2n=1+4+…… 4^(n-1)+4+4^2+…… 4^n=5(4^n-1)/3
The way is like this. You can see for yourself, right

How to say in English?
It's better to write in Chinese characters, and the pronunciation seems to be alon Nao
How to read know?

I don't know
I'm not sure. I have no idea

The area of Tiananmen Square is about 440000 square meters. Please estimate that one millionth of it is equivalent to ()
A. Area of classroom floor B. area of blackboard C. area of desk D. area of pencil box

440000 square meters = 440000 square meters, 440000 × 11000000 = 0.44 square meters, less than half a square meter, should be the area of the desk

It is meaningful to know the power 0 of (X-2) - 3 of (x-1) - 2. Try to find the value range of X
Please explain the layout

The power 0 of 0 is meaningless
So X-2 ≠ 0
x≠2
The - 2 power of (x-1) = 1 / (x-1) & sup2;
The denominator is not equal to 0
So x12 ≠ 0
x≠1
So x ≠ 1 and X ≠ 2

How to write surprise English words and phonetic symbols?

pleasantly surprised