Z = f (XY, x ^ y), find DZ

Z = f (XY, x ^ y), find DZ

DZ = the partial integral of Z to X * DX + the partial integral of Z to y * dy when seeking the partial integral, you wake up when you regard another variable as a constant. It's hard to play special symbols. Read more books

Let z = sin (XY) 2x square y, find the total differential DZ

According to the rules, you need to be patient and try to avoid small mistakes
Find Z first_ x = cos(xy) y (2x^2)y + sin(xy) (4x) y
Find Z again_ y = cos(xy) y (2x^2)y + sin(xy) (2x^2)
dz = z_ x dx + z_ y dy
Bring in the above formula

Given 3x-5y = 0, then the value of fraction x − 2yx + 3Y is______ ．

∵ 3x-5y = 0, ∵ x = 5y3, ∵ original formula = 5y3 − 2y5y3 + 3Y = - 111

Party A and Party B start from place a at the same time and go in the same direction. Party A starts first, and Party B pursues Party A at a speed of 80 kilometers per hour half an hour later. If Party B overtakes Party A after 3.5 hours, what is the speed of Party A per hour

When B catches up with a, the distance between them is equal. If a travels half an hour more than B, that is 0.5 hours, then a travels 3.5 + 0.5 = 4 (hours), and the distance of B is 80 × 3.5 = 280 (kilometers), so a also travels 280 meters, and a's speed is 280 △ 4 = 70 (kilometers / hour)
A: the speed of a is 70 km / h

It is proved that n →∞ limsinnx / N = 0 holds for any real number by the pinch theorem
Hurry

So n →∞ limsinnx / N = 0

The two trains run in opposite directions. Train a runs 80 kilometers per hour with a body length of 150 meters, while train B runs 100 kilometers per hour with a body length of 120 meters
Then the time from the front of the car to the rear of the car is

1 when x is needed for solution
80000x＋100000x＝150+120
The solution is x = 0.0015
0.0015 hours = 5.4 seconds

The average of the three numbers is 60, and the ratio of the three numbers is three to two to one

30＞20＞10

The sum of five consecutive even numbers is 130, and the five consecutive even numbers are ()
Come on, OK, I'll give you a bonus

X+X+2+X+4+X+6+X+8=130
5X+20=130
5X=110
X=22
22 + 24 + 26 + 28 + 30 = 50 + 50 + 30 = 130 (correct)

A number consists of eight million, six hundred thousand, seven thousand, forty tens, six 0.1 and five 0.01. This number is ()

8607040.65

On the map of 1:4000000 scale, the distance between a and B is 8 cm. A and B drive from two places at the same time and meet each other two hours later
It is known that the speed ratio of car a and car B is 2:3?

A. B actual distance between the two places = 8 △ 1 / 4000000 = 32000000cm = 320km
Speed sum of vehicle a and B = 320 △ 2 = 160 km / h
Speed of car a = 160 × 2 / (2 + 3) = 64 km / h
Vehicle B speed = 160-64 = 96 km / h