Factorization: the square C of 18 (a + b) and the square C of 2 (a-b)

Factorization: the square C of 18 (a + b) and the square C of 2 (a-b)

Factorization of the square of a-the square of b-ac + BC

The square of a - the square of B - AC + BC
=(a+b)(a-b)-c(a-b)
=(a-b)(a+b-c)

Equations (x-3 / 2) + 3 greater than or equal to x 1-3 (x-1)
Equations (x-3 / 2) + 3 greater than or equal to X
1-3（X-1)

(x-3 / 2) + 3 is greater than or equal to X
x-3+6≥2x
x≤3
1-3（X-1)-2

Solution: let the three sides of the triangle be 15,19,23, reduce the three sides to x cm, fold the triangle into an obtuse angle triangle, and find the value range of X
Thank you, brother and sister. Hurry up
The exact steps to be taken

The first is to judge the condition of triangle
The sum of the two sides is greater than the third side
The difference between the two sides is less than that of the third side
(15-x)+(19-x)>23-x
23-x-(15-x)(23-x)^2
That's it
What accurate steps do you need if you don't study hard?
Make a system of equations!
(15-x)+(19-x)>23-x
23-x-(15-x)(23-x)^2
Find a minimum range
Don't ask if you want to solve the equations

When - 2 "X"

x^2-2ax＜0
（x-2a)x＜0
There are two situations
1 a＞0
The solution set of inequality is (0,2a), but according to the meaning of the problem, the solution set of inequality must contain the value range of X. This solution set does not satisfy the condition, so it is discarded
2 a＜0
The solution set of inequality is (2a, 0)
So, 2A

Let z = (x ^ 2 + y ^ 2) ^ XY find the partial derivative

The partial derivatives of X and y are the same. Only the partial derivatives of X are considered
Let's fix y to derive x, and let's take ln as well
lnz=xyln(x^2+y^2)
For the two sides, u '* 1 / u = (xyln (x ^ 2 + y ^ 2))'
It is easy to get (xyln (x ^ 2 + y ^ 2)) '= YLN (x ^ 2 + y ^ 2) + 2yx ^ 2 / (x ^ 2 + y ^ 2)
Then u '(x) = (YLN (x ^ 2 + y ^ 2) + 2yx ^ 2 / (x ^ 2 + y ^ 2)) * (x ^ 2 + y ^ 2) ^ XY
Interim * denotes multiplication

How many pieces are there in the outermost layer of square array pieces? What is the total number of pieces?

Total 8 * 8 = 64, outer 4 * 8-4 = 28

As shown in the figure, there is a parabolic arch overpass. The maximum height of the arch is 16m and the span is 40m. Now put it in the rectangular coordinate system as shown in the figure. If you want to erect an iron column at m5m away from the center of the span to support the vault, how long should the iron column be?

From the meaning of the question, we know that the vertex coordinates of the parabola are (20,16), and the point B (40,0). Let the parabola be y = a (x-20) 2 + 16. ∵ point B (40,0) is on the parabola, ∵ a (40-20) 2 + 16 = 0, ∵ a = - 125. ∵ y = - 125 (x-20) 2 + 16. ∵ when x = 15, y = - 125 (15-20) 2 + 16 = 15m; when x = 25, y = - 125 (25-20) 2 + 16 = 15m

It is known that the image of inverse scale function y = K / X passes through points (2, - 2). (1) when x = 4, find the value of Y

Substitute x = 2, y = - 2 into y = K / X because y = x / K
So k = XY
So k = 2 * (- 2)
k=-4
So y = - 4 / X
Substituting x = 4, the solution is y = - 4 / 4
y=-1

If A2 + 3AB = 4, 5ab + 2B2 = 2, then the value of 2a2-9ab-6b2 is ()
A2 is the square of A

It's two