How to calculate 3x + 4 / 5 = 4 / 5?

How to calculate 3x + 4 / 5 = 4 / 5?

3x=4/5-4/5=0,x=0

Definition of positive definite matrix
Can we simply understand that a positive definite matrix is a matrix in which every term is a positive number

For a general matrix, it can be said that the matrix should be transformed into a standard form
If a matrix is positive definite, the real quadratic form f (x1, X2,..., xn) corresponding to the matrix has f (C1, C2,..., CN) > 0 for any group of real numbers C1, C2,..., CN which are not all zero

It is known that the general formula of an is an = (3x-1) ^ n. if the limit of an exists, then the value range of real number x is

|3x-1|

Find the unknown. 1.9x + 1.7x = 10.8 4x △ 4 / 5 = 2 / 3, 3 / 4 + 1 / 2, x = 4 / 5
Find the unknown
1.9x+1.7x=10.8
4x △ 4 / 5 = 2 / 3
3 / 4 + 1 / 2 x = 4 / 5

Hello: 1.9x + 1.7x = 10.83.6x = 10.8x = 3 4x △ 4 / 5 = 3 24x = 2 / 3x4 / 54x = 8 / 15x = 2 / 15 3 / 4 + 1 / 2 x = 4 / 5-3 / 41 / 2x = 1 / 20x = 1 / 10

It is known that the definition field of function f (x) is [0,1], and satisfies the following conditions: ① f (x) = - 3, ② f (1) ≤ 1, and ③ if x1 ≥ 0, X2 ≥ 0, X1 + x2 ≤ 1
Then f (x1 + x2) ≤ f (x1) + F (x2) - 1
(1) The value of F (0), (2) the value of function f (x)!
(2) Is to find the maximum value of F (x), ① is f (1) = - 3, ③ is f (x) ≤ 1

① F (x) = - 3 are you sure this condition is correct?

The function y = cos2x is an increasing function in which of the following intervals

Monotonically increasing on (- Π / 4 + K Π / 2, Π / 4 + K Π / 2), K ∈ R

There is a square with side length of 1 and a rectangle with side length of 1 and root number of 2, which are divided into two triangles by their diagonals
What's the volume of a pyramid made of these four triangles?
Please answer in detail, especially how to find the height of triangular pyramid, thank you very much

1 / 6 first of all, draw a three-dimensional figure according to the given side length relationship. It is not difficult to find that the triangle with side length of 1,1 and root 2 is the bottom, then the triangle with side length of 2, root 3,1 and the common edge of the triangle with side length of 1,1 and root 2 are vertical to the ground, so the common edge is high, and its value is 1, so the volume is 1 / 3 times the bottom area times high, and 1 / 6 is obtained

5-x²-xy+y²=-（ ）-（xy-5）
Quick, urgent, give me an accurate answer, and say why, take it, thank you

5-x²-xy+y²=-（x²-y²）-（xy-5）
If you don't understand, I wish you a happy study!

3.2 + 7.2x = 19.2 (solving equation)

3.2+7.2x=19.2
7.2x=16
x=20/9

Given the ellipse x ^ 2 / 4 + y ^ 2 / 9 = 1, the slope of a group of parallel lines is 3 / 2. When the line intersects the ellipse, it is proved that the midpoint of the line segment cut by the ellipse is on a line

The straight line is y = 3 / 2 × x + C
Bring in the elliptic equation
We get x = - 1 / 3 * C plus and minus (7 / 9 × C ^ 2-2) ^ 0.5, y = 1 / 2 * C plus and minus 3 / 2 * (7 / 9 * C ^ 2-2) ^ 0.5
All midpoints are (x, y) = (- 1 / 3 * C, 1 / 2 * c)
On the line y = - 2 / 3 * x