Let f (x) = - 1 / 3x ^ 3 + ax have three monotone intervals, then the value range of a is

Let f (x) = - 1 / 3x ^ 3 + ax have three monotone intervals, then the value range of a is

a＞0

Given the function f (x) = ax ^ 3-3x ^ 2 1-3 / A, if the function f (x) increases monotonically in [2,4], find the value range of A
Detailed process >_

If f '(x) is derived to f' (x) = 3ax ^ 2-6x = 3A (x-1 / a) ^ 2-3 / A, then f '(2) > = 0, f' (4) > = 0, then a > = 1 is obtained

The partial derivative can also be called the existence of partial derivative

No
Partial derivative is derivable, which means that the reciprocal of partial derivative can be obtained (for the original function, quadratic partial derivative)
Differentiable partial derivatives must exist
But the existence of partial derivatives is not necessarily differentiable

There is a pile of chessmen. Put them into a square with side length X. x is an integer, and the number of chessmen in each row and column is the same. At this time, there are still 8 chessmen left. If you put them into a square with side length x, X is an integer
A square with a side length of (x + 1) is 9 pieces short. How many pieces are there in this pile?

8+9=17
(17-1)×4+8=72
（17+1）×4

What is the possible image of the function y = ax & sup2; + A and y = A / X (a ≠ 0) in the same coordinate system

If a > 0, then y = ax & sup2; + A is in the first two quadrants and y = A / X is in the first three quadrants
If a

On the function of X, y = k-1 / x + K ^ 2-1 is an inverse proportion function, so we can find the value of K

If y = k-1 / x + K ^ 2-1 is an inverse proportional function, then
k²+k--1=0
K = (- 1 plus minus root 5) / 2

First, simplify: [a ^ 2-B ^ 2] / [a ^ 2-AB] / (a + [2Ab + B ^ 2 / a]). When B = - 1, please choose an appropriate formula for a to evaluate
2. When m is a value, the solution of the equation 3 / X-6 / 1-x = x + m / x ^ 2-x is positive

1、[a^2-b^2]/[a^2-ab]÷（a＋[2ab＋b^2／a]）=(a+b)(a-b)/[a(a-b)]÷(a+b)^2/a
=[(a+b)/a]*[a/(a+b)^2]
=1/(a+b)
When B = - 1, a = 0
Original formula = 1 / (0-1) = - 1
2. Simplification 3 / x + 6 / (x-1) = (x + m) / [x (x-1)]
3 (x-1) + 6x = x + m (obviously x ≠ 0,1)
8x=m+3
x=(m+3)/8
It is known that the solution of the equation is positive
Then (M + 3) / 8 > 0 and (M + 3) / 8 ≠ 1
The solution is m > - 3 m ≠ 5
That is, when m > - 3 and m ≠ 5, the solution of the equation is positive

As shown in the figure, in the triangle ABC, ab = AC, ∠ abd = ∠ ACD, the intersection e of the extended bisector BC of AD, to prove AE ⊥ BC

Certification:
∵AB=AC
∴∠ABC=∠ACB
∵∠ABD=∠ACD
∴∠DBC=∠DCB
∴△ABD≌△ACD（SAS）
∴∠BAD=∠CAD
Ψ ad is the bisector of ∠ BAC
⊥ AE ⊥ BC (the bisector of the vertex angle of an isosceles triangle is also the height at the bottom)

How many square centimeters is 3.09 square decimeters minus 45 square centimeters?
There are still two problems: 10.5m = 90dm +? Cm 0.5 yuan =? Min + 0.8 Jiao

How many square centimeters is 3.09 square decimeters minus 45 square centimeters?
A: 364 square centimeters
10.5m=90dm+?
A: 15dm
RMB 0.5 =? Min + 0.8 Jiao
42 points

Judge that the two quantities are not in proportion
1. The divisor is definite, the divisor and quotient
2. A road, repaired and not repaired
3. The length of the top and bottom of the trapezoid is certain, the area of the trapezoid and its height
4. The area of each brick is fixed, the number of bricks and the floor area
5. Dig a canal, the number of participants and the time required
6. The time and speed required to travel from place a to place B
7. A certain unit area, sowing area and total yield
Time, speed and distance
9. The number of copies and money needed to subscribe to Beijing children
What proportion is written in ()

1. In inverse proportion
2. Out of proportion
3. Proportional to
4. Proportional to
5. In inverse proportion
6. In inverse proportion
7. What does unit area mean If it refers to the area of a crop, then it is proportional
8. Proportional to
9. Proportional to