Let z = f (XY, e ^ x + y) and find DZ Advanced numeral problems, waiting for great Xia

Let z = f (XY, e ^ x + y) and find DZ Advanced numeral problems, waiting for great Xia

dZ=Zxdx+ Zydy.Zx=yf1 +E ^ (x + y) f 2, ZY = XF 1 + e ^ (x + y) f 2. F 1 denotes that f computes the partial derivative of the first variable, F 2 denotes that f computes the partial derivative of the second variable. By substitution, DZ = (YF 1 + e ^ (x + y) f 2) DX + (XF 1 + e ^ (x + y) f 2) dy is obtained

A truck can save 4 / 7 kg of gasoline when traveling 10 km. How many kg of gasoline can be saved when traveling 1 km?
Hongxing primary school burned five and a half of the coal in April, one twentieth less than in March. How many tons more coal was burned in March than in April?
There are 120 male and female workers in a factory. If the female workers are transferred by one tenth and the male workers are increased by 41, the number of female workers is equal. How many male and female workers are there?

A truck can save 4 / 7 kg of gasoline when traveling 10 km, and how many kg of gasoline can be saved when traveling 1 km? 4 / 7 △ 10 = 2 / 35 kg. Hongxing primary school burns 5.1 / 2 tons of coal in April, which is 20% less than that in March. How many tons more than that in April? 5.1 / 2 △ 1 / 20 = 5.5 △ 19 / 20 × 1 /

Is the complement of vertex equal?
As the title

The vertex angles are equal, so their complement angles are equal

U & # 178; + V & # 178; - X & # 178; - y = 0 - U + v-xy + 1 = 0 find & # 8706; U / &# 8706; X, &# 8706; V / &# 8706; X

x. Y is an independent variable, and the formula is partial derivative to X
U & # 178; + V & # 178; - X & # 178; - y = 0, derivative X
2uu' + 2vv' - 2x = 0
uu' + vv' - x = 0(1)
-u+v-xy+1=0
-u'+v'-y=0(2)
LIANLI (1) (2)
Solution u ', V'

When the crystal melts, it will continue to absorb heat, the temperature remains unchanged, but the internal energy will not increase

It will increase

How many times faster is light than sound?

It is about 340m / s or 1224km / h at a standard atmospheric pressure and 15 ℃
The speed of light is 300 million meters per second
So it's about 882, 352 times, if it's at standard atmospheric pressure

If loga (2) > log2 (a), then the value range of a is____ .

lg2/lga>lga/lg2
0

How many degrees is 23 ° 36'36 "equal to 34.26 ° equal to several degrees, minutes and seconds

23 ° 36 ′ 36 ″ = 23 ° + 36 minutes + 36 △ 60 minutes = 23 ° + 36.6 minutes = 23 ° + 36.6 △ 60 degrees = 23 ° + 0.61 degrees = 23.61 degrees 34.26 degrees = 34 degrees + 0.26 × 60 minutes = 34 degrees + 15.6 minutes = 34 degrees + 15 minutes + 0.6 × 60 seconds = 34 degrees 15 minutes 36 seconds

The ratio of the sum of odd and even terms in arithmetic sequence
The total number of items is even

The total number of items is even
Suppose 2n terms
Then the odd term is n
The first is A1, and the last is a (2n-1)
So sum = [A1 + a (2n-1)] n / 2
The even term is the one under n
The first is A2 and the last is A2N
So sum = (A2 + A2N) n / 2
Ratio = [A1 + a (2n-1)] / (A2 + A2N)
Because A2 = a1 + D
a(2n-1)=a2n-d
And A2N = a1 + (2n-1) d
So ratio = [A1 + A1 + (2n-1) D-D] / [A1 + A1 + (2n-1) d + D]
=(2a1+2nd-2d)/(2a1+2nd)
=(a1+nd-d)/(a1+nd)
=an/a(n+1)

(2 √ 3-3 √ 6) square

66-36√2