If (x-2y) ^ 2 = x ^ 2 + 2XY + 4Y ^ 2 + m, then M =?

If (x-2y) ^ 2 = x ^ 2 + 2XY + 4Y ^ 2 + m, then M =?

Because (x-2y) ^ 2 = x ^ 2-4xy + 4Y ^ 2
So m = - 6xy

Given that the square of (x-2y) = the square of X + 2XY + the square of 4Y + m, then M is

(x-2y)^2=x^2-4xy+4y^2=x^2+2xy+4y^2+M
So m = - 6xy

Given that f (x) is continuous from negative infinity to positive infinity, and f (0) = 2, Let f (x) = ∫ f (x) DX be the definite integral from x square to SiNx, and find the solution of F '(0)

F'（x）=(cosx-2x)f(x)
F‘（0）=（1-0）f（0）=2

Why does the rank of two matrices become smaller after multiplication?

This is because of the row or column vector group of the product matrix
It can be expressed linearly by row or column vectors of the original matrix

On the quadratic equation of one variable
If 2 is a root of the equation 3 / 2-2a = 0 about X, what is the value of 2a-1
If 2 is a root of the equation 3 / 2x & # 178; - 2A = 0 about X, then what is the value of 2a-1

Substitute x = 2 to get the value of A

The area of rectangle is expressed by letter formula

Rectangle area = length × width
Letter formula: S = AB (where s is area, a is length, B is width)

It is proved that the inequality X / (1 + x) is less than arctan, X is less than x, where x is greater than 0

Let f (x) 1 = x / (1 + x)
f（x）2=arctanx
f（x）3=x
It is easy to know that the derivatives of the above three functions increase in turn by combining with x > 0;
When x = 0, the values of the above three functions are equal, and the derivatives increase in turn;
It is easy to know the conclusion;

Do whatever you want
43.7-three eighths + 16.3-8.625 two and one sixth + (5.2-five and one fifth) × five thirds

43.7-3 / 8 + 16.3-8.625
=(43.7+16.3)-(3/8+8.625)
=60-9
=51
Two and one sixth + (5.2-five and one fifth) × five thirds
=13/6+(5.2-5.2)x5/3
=13/6

How to solve the following mathematical geometry problems
For right triangle ABC with side lengths of 16 and 20, ∠ C = 90 ° take point C as the vertex, make equilateral triangle inside the triangle, and the other two points are on the side of the triangle

Do CD ⊥ AB through C
So CD is not only the height of the bottom edge ab of RT △ ABC, but also the height of the equilateral triangle
The length of the hypotenuse can be known from the two right angles,
The area can be used to get the height
According to the height and side length of equilateral triangle, it is high: side length = √ 3:2
You can get the length of the equilateral triangle

If the square of a plus AB equals 4 and the square of AB plus B equals minus one, find the square of a minus the square of B

a-b=(a+ab)-(ab+b)=4-(-1)=5.