The equation of a circle passing through point P (- 2,4) and having the common chord of two circles x ^ 2 + y ^ 2-6x = 0 and x ^ 2 + y ^ 2 = 4 as one chord is?

Let x ^ 2 + y ^ 2-6x + k * (x ^ 2 + y ^ 2-4) = 0 be substituted into P (- 2,4) point coordinate to get: (- 2) ^ 2 + 4 ^ 2-6 * (- 2) + k * (- 2) ^ 2 + 4 ^ 2) - 4) = 0 solution to get: k = - 2, so the equation is: x ^ 2 + y ^ 2-6x-2 * (x ^ 2 + y ^ 2-4) = 0. Simplify to: x ^ 2 + y ^ 2 + 6x-8 = 0 or: (x + 3) ^ 2 + y ^ 2 = 17. If there is any error, please fill in

The meaning of decimals in life
1. Liu Xiang won the gold medal in Athens with 12.91 seconds
2. Guo Jingjing won the gold medal with 633.15 points in the final of women's 3m springboard diving in Athens Olympic Games
3. Wang Yifu won the title again with 690.0 rings in Athens Olympic Games
Please tell me the meaning of the above decimals

1. 12 and 91 percent

A rectangle with a circumference of 46 decimeters, if the length and width increase by 10 cm, then the area will increase______ Square decimeter

As shown in the figure, if the length of the original rectangle is a and the width is B, then a + B = 46 △ 2 = 23 decimeters and 10 cm = 1 decimeters, so the area is expanded by a × 1 + B × 1 + 1 × 1 = a + B + 1 = 23 + 1 = 24 (square decimeters); therefore, this question should be filled in 24.1 decimeters

When a small object m is placed on a spring oscillator which moves harmonically in the vertical direction, its amplitude changes and its kinetic energy changes in the original equilibrium position

Let the mass of the original spring oscillator be m, the velocity at the balance position of the oscillator be V, and the progress coefficient of the spring be K
When m is placed, it is obviously completely inelastic collision. According to the conservation of collision supersymmetric momentum, the velocity after collision can be obtained as V '= MV / (M + m). The kinetic energy of the new oscillator at the element equilibrium position is e' = 0.5 (M + m) * V '^ 2 = 0.5 (MV) ^ 2 / (M + m) = 0.5m * V ^ 2 * m / (M + m), It is obviously less than the original kinetic energy here. As for the change, just reduce it
As for the amplitude, I made a mistake just now and revised it as follows
If the new oscillator is moving downward at this time, suppose that it can descend to the place where x is stationary at most, then there is 0.5kx ^ 2 = e '+ (M + m) GX. If e' is brought in, X can be obtained by solving the equation, so the amplitude of the new oscillator is a '= x - mg / K, and the amplitude of the original oscillator is a = SQR (MV ^ 2 / k). The amplitude variation is equal to a - a'
Or from the angle of energy amplitude, the total energy of the new oscillator relative to the new equilibrium position is e '+ (M + m) g * mg / k = 0.5 (MV) ^ 2 / (M + m) + (M + m) g * mg / K, and the total energy of the original oscillator is 0.5mv ^ 2

Cut a 20 cm square cardboard into a rectangular paperboard without cover,
In order to make its volume larger than 550 cubic centimeters, regardless of seams and losses, what is the length, width and height of the carton (unit: cm)

Draw a picture below, we can see that using a piece of square cardboard with side length of 20cm to cut and paste into a cuboid carton without cover is to cut out four identical squares at four corners. Cutting out the side length of the square is the height of the cuboid carton, and its length and width are equal to 20. Cutting out the side length of two squares, the length, width and height must be

The difference between speed and speed
I'm tutoring senior one
I think so
Because the speed is the ratio of displacement to time, even if a car runs a big circle and finally returns to the starting point, the speed is still 0 km / h, but how to explain the speed on the dial?
Speed is the distance divided by time, as long as you start driving, it will never be 0
Which is the speed in junior high school?

Velocity is a vector, which has size and direction. Velocity is calculated by displacement divided by time. Velocity is a scalar, which only has size but no direction. The formula divides time by distance, but it is consistent in formula form, which is v = s / T
Typing is not easy,

As shown in the figure, OA is the vertical line from the center O of the bottom surface of the cone to the generatrix. If OA rotates around the axis for one circle, the surface will divide the cone into two parts with equal volume, then the cosine value of the angle between the generatrix and the axis is ()
A. 132B. 12C. 12D. 142

As shown in the figure, let ob = 1, then od = CTG θ, AC = ad · sin θ, OD · cos θ, sin θ = Cos2 θ, V-cone DBB ′ = π 3ctg θ, V-cone OAA ′ = 13Do · π ac2 = 13ctg θ· π Cos4 θ. From the meaning of the question, cos 4 θ = 12, so cos θ = 142

Put the correct serial number in brackets
1. There are () divisors of 6
①3 ②4 ③6
2. The number that can be divisible is ()
① Composite number ② odd number ③ even number
3. The following number formula can be transformed into a finite small tree is ()
①5/8 ②5/6 ③7/30

2、1、1

There are two circles, big and small. Their area difference is 160 square centimeters. It is known that the perimeter ratio of the two circles is 5:3. What is the area of the big circle?

If the perimeter ratio of the two circles is 5:3, the radius ratio is 5:3 and the area ratio is 25:9
160/（25-9）=10
So the area of the big circle is: 25 * 10 = 250

The formula and reasoning idea must be easy to understand!

First calculate the perimeter of the bottom edge, this is simple, and then calculate the vertical distance between the upper bottom and the lower bottom. Just multiply the two, because the side of the oblique prism is a parallelogram
I don't know for myself, do I

The equation of a circle passing through point P (- 2,4) and having the common chord of two circles x ^ 2 + y ^ 2-6x = 0 and x ^ 2 + y ^ 2 = 4 as one chord is?