Where is the stationary point of the cubic power of y = 2x - 6x square - 18x + 73 Where 6x square - 12x - 18 comes from? I don't know what derivative is

Where is the stationary point of the cubic power of y = 2x - 6x square - 18x + 73 Where 6x square - 12x - 18 comes from? I don't know what derivative is

y=2x³-6x²-18x+73
y'=6x²-12x-18=0
This is the derivative
Because the stationary point is the point where the derivative is equal to 0, the derivative must be obtained

Let X and y satisfy the constraint conditions 1, 3x-y-6 ≥ 0,2, X-Y + 2 ≥ 0,3, x, y greater than or equal to 0. If the maximum value of the objective function z = ax + B (a, b > 0) is 12, then the minimum value of a ^ 2 + B ^ 2 is 12
A. 6 / 13 B, 36 / 5 C, 6 / 5 d, 36 / 13 this problem baffled our math teacher, is the problem of Wuhan city
I think it should be z = ax + by, but the original problem is that there is no y, that is, the maximum value of Z = ax + B is 12

From the meaning of the title, 4A + 6B = 12
The square of the distance from the origin to the line 2A + 3b-6 = 0 is a ^ 2 + B ^ 2
[6/√(13)]^2=36/13

There are two piles of cement. Pile a is 4.5 tons. It is known that 4 times the mass of pile a is equal to 3 times the mass of pile B, so how many tons of pile B cement is there

The cement in pile B is 4.5 △ 4 △ 3 = 6 tons

If we know that the image of a linear function y = (m-2) x-3 is only the second quadrant, then the value range of M is?

First of all, for the function of y = KX + B, we can summarize several rules: 1. When the image is not in the first quadrant, K ≤ 0, B < 02. When the image is not in the second quadrant, K ≥ 0, B < 03. When the image is not in the third quadrant, K ≤ 0, b > 04. When the image is not in the fourth quadrant, K ≥ 0, b > 0

The ratio of boys to girls in a class is 3:2. It is known that there are 30 boys and how many girls?

If the ratio of male to female is only 3:2, boys account for 3 / 5 of the total number, and there are 30 boys, then the total number is 50, 50-30 = 20, that is, the number of girls

The range of y = radical (X-2) / x + 4
The root includes X-2

X-2 > = 0, X is not equal to 0, so x > = 2, when x = 2, the function y is the minimum, and the minimum value is 4, so the function range is [4, positive infinity]

The students are playing games. The ratio of male to female is 3:2. Then four girls are added. At this time, boys account for 5 / 9 of the total number

Set the original number of boys as 3x, the original number of girls as 2x
3X/(2X+4)=5/9
X=10
3X=30
2X=20
The original number of boys was 30, and that of girls was 20

When m is a real number, the quadratic equation x ^ 2 + 2mx + m + 2 = 0 has two unequal negative roots?

△＞0
（2m）²-4（m+2）＞0
4m²-4m-8＞0
4（m+1）（m-2）＞0
Negative root
m+1＜0 m-2＜0
m＜-1

There are 18 girls in class 61, accounting for 40% of the total number of students

18 divided by 40% = 45
Because 18 accounts for 40% of the total, is to seek the total
Then you can set the total amount to X
It can be 18 = 40% X of the column
After simplification, the first formula

Add and subtract, and then add and subtract

Strike, plus "ten" and minus "one", the prescription is to open the mouth "凵". Ten, one and 凵 are combined as "strike"