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Finding the total differential Du of the function u = ln (2x + 3Y + 4Z ^ 2)
Total differentiation on both sides of an equation
du=【1/(2x+3y+4z^2)】【2dx+3dy+8zdz】
Total differential Du of function u = sin (x + y + Z) + 2007=_______
∂u/∂x=cos(x+y+z)
∂u/∂y=cos(x+y+z)
∂u/∂z=cos(x+y+z)
So Du = cos (x + y + Z) DX + cos (x + y + Z) dy + cos (x + y + Z) DZ
If a three digit number is divided by 43, the quotient is a and the remainder is B, then the maximum value of a + B is? 33______ 957______ 64______ 56______ ．
The divisor is 43, the remainder B is 42, the divisor is 43A + B = 43A + 42, = 43 (a + 1) - 1, so the divisor is the multiple of 43-1, because 23 × 43 = 989, 24 × 43 = 1032, when the divisor is 989, the value of a + B is the maximum, that is, a + 1 = 23, a = 22, 22 + 42 = 64, a: the maximum value of a + B is 64
The old lady opened a window for her?
Because the old lady brought hope to the little girl in her infinite sorrow, which made her no longer melancholy and happier
The Enlightenment of "dripping wears away stone"
Water drips through the stone. When you see this topic, you must think that water drips on the stone and finally drips through the stone. I used to think that way. I didn't know the profound meaning until I read the article "Enlightenment of water drips through the stone". This paper mainly talks about: there is a great spectacle in the Taiji cave in Guangde, Anhui Province
If 3x-9 = 3, then (3x-9 + 9) △ 3 = (3 (sign) number) sign number
Add 9 and divide by 3
（3x-9+9）÷3＝（3（+）9）÷ 3
0.99 × 102 for simple operation!
It's a recursive equation!
Which of the two is right?
0.99×102
=0.99×（100+2）
=0.99×100+0.99×2
=99+1.98
=100.98
The extensive exploration of 22.2 on page 43 of mathematics volume 1 of grade 9 questions 13 and 14
There is no positive integer solution for 1 / 2n (n-2) = 18
14. There are always two unequal real roots, because B ^ 2-4ac = 1 + P ^ 2 > 0
The price of a commodity first increases by 1 / 10, and then decreases by 1 / 10. The current price is 49.5 yuan. What's the original price
Original price
=49.5÷（1-10%）÷（1+10%）
=49.5÷0.9÷1.1
=50
Find the monotone interval of the following functions in the domain of definition~
1. The square of y = x - 2x
2. The third power of y = x
3. The square of y = 1 / X
1. In (- ∞, 1) monotone decreasing, (1, ∞) monotone increasing
2. Monotone increasing function
3. In (- ∞, 0) (0, ∞) are monotone increasing functions
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