Known equation x2 + y2-2 (T + 3) x + 2 (1-4t2) y + 16t4 + 9 = 0 When t is the value, the radius of the equation is the largest

Because x2 + y2-2 (T + 3) x + 2 (1-4t2) y + 16t4 + 9 = 0, so (x-t-3) ^ 2 + (y + 1-4t ^ 2) = (T + 3) ^ 2 + (1-4t ^ 2) ^ 2-16 ^ 4-9 = 1 + 6t-7t ^ 2, when the radius is maximum, i.e. 1 + 6t-7t ^ 2 gets the maximum value

Is atomic model an electron cloud model?

The two models do not conflict
The atomic model considers that the atom is composed of nucleus and extranuclear electrons
The electron cloud model also considers that atoms are composed of nuclei and extranuclear electrons
However, the electron cloud model is more detailed. It holds that the electrons outside the nucleus do not have orbits, but appear in some regions in the form of probability. The region where the electrons may appear is called "cloud", which is also recognized in quantum mechanics
Leave a message if you have any questions

Which of the atomic planet model, the electron cloud model of helium atom and the atomic raisin cake model is closest to the real situation inside the atom?
Or are the three approaches the same?

Atomic raisin cake model has been denied for a long time, which is a preliminary understanding of atoms. Atomic planet model plays a certain role in explaining atomic spectrum and other problems, but experiments show that electrons have no definite orbit, which is inconsistent with the fact. Atomic electron cloud model is more in line with the real situation

The atomic structure model closest to the actual atomic structure is () a layered model B electron cloud model C Thomson model d Rutherford model

Choose B
The motion of electrons outside the nucleus is not orbital distribution, but satisfies the wave function, which is the electron cloud model

What are the basic units in the international system of units?

Length: M
Mass: kg
The mass of 1000 cubic centimeters of pure water at 4 ℃,
Time: seconds (s)
Current: Ampere (a)
Thermodynamic temperature: Kelvin (k)
Luminous intensity: candela (CD)
Amount of substance - (mol)

The masses of blocks a and B are M1 and M2 respectively, and they are connected by light springs with stiffness and coefficient K. first, lift a vertically upward by hand, so that B has no pressure on the ground

m1g=k1×l1
m2g+k1×l1=k2l2
Ep1=(1／2)k1×l1∧2=m1∧2g∧2／2k1
Ep2=
I'm left with my own solution

One square kilometer is equal to several mu

1 square kilometer = 1 500 mu (from Baidu measurement)
One hectare is equal to 15 mu, one mu is equal to 60 square feet, 15 mu is equal to one hectare, and one mu is about 667 square meters

The gravity of a metal ball in the air measured by a spring scale is 45 n. immerse it in water, and the indication of the spring scale becomes 34 n
How much buoyancy does the metal ball bear?
What is the volume of the ball? (g = 10N / kg)

In water, the metal ball is subjected to upward buoyancy and downward gravity. The spring scale has an indication, which indicates that gravity is greater than buoyancy. The difference between gravity minus the indication of the spring scale is the buoyancy
So:
F = 45-34 = 11 (n)
According to Archimedes theorem: F floating = ρ liquid GV row
In this problem, ρ = 1.0 × 10 & # 179; kg / M & # 179;
V row = volume of metal ball (V gold)
｛ 11 = 1.0 × 10 & ｛ 179; × 10 × V gold
1 × 10 ＾ (- 3) m and ᦇ 179;

It is known that the circumference of a rectangle is 10cm. Let one side of the rectangle be xcm and the other side YCM. (1) write the analytic function between Y and X
Let's know that the circumference of a rectangle is 10cm. Let's set the length of one side as xcm and the length of the other side as YCM. (1) write the analytic expression of the function between Y and X and the value range of the independent variable x; (2) please draw the image of the function in the plane rectangular coordinate system. Also, draw the number of the coordinate system in the image
To get the image of the function: (1) write the analytic expression of the function between Y and X and the value range of the independent variable x; (2) please draw the image of the function in the plane rectangular coordinate system. And you have to draw the number of the coordinate system in the image.

I'm dizzy. So the problem of Pediatrics was not learned in junior high school
2X+2Y=10
Then y = 5-x (0

How about the size of rice packaging bag? Including 5kg 10kg 15kg 20kg 25kg 50kg?
Among them, 5kg is vacuum compression packaging, and others are woven bag materials

5kg:30*48
10kg: 35 * (58-60) (without portable) with portable: 35 * (60-62)
15kg：40*65
20kg: unknown
25kg：45*75
50kg：55*100

Known equation x2 + y2-2 (T + 3) x + 2 (1-4t2) y + 16t4 + 9 = 0 When t is the value, the radius of the equation is the largest