Is that density?

Is that density?

The density of water is 1000g / cm3

It is known that: 14 (B-C) 2 = (a-b) (C-A), and a ≠ 0, then B + C4A = 0___ ．

14 (B-C) 2 + BC = (a-b) (C-A) + BC, reduction: 4a2-4a (B + C) + (B + C) 2 = 0, 4-4b + Ca + (B + C) 2A2 = 0, that is: (2-B + Ca) 2 = 0, then B + C4A = 12, so the answer is: 12

If point a (3,4), f is the focus of parabola y2 = 2x, and point m moves on the parabola, what is the coordinate of point m when Ma + MF is the minimum

According to the definition of parabola, the value of MF is equal to the distance from m to the parabola directrix. When Ma + MF takes the minimum value, it is the intersection point of the straight line passing through AM and the parabola when it is parallel to the X axis
So my = 4, substituting y2 = 2x, we get x = 2
M (2,4)

The piston area of a single cylinder four stroke gasoline engine is 30 square centimeter. The distance that a stroke piston moves in the cylinder is 50 mm. The average pressure of gas on the working stroke is 9.0 times 10. The flywheel rotates 1800 cycles in 1 minute. The average pressure of gas on the piston in one working stroke is calculated. The power of gasoline engine is calculated

(1) Average pressure of gas to piston: F = PS = 9.0 × 10 5 Pa × 30 × 10 - 4 M2 = 2.7 × 10 3 N (2) work of gas to piston: w = FS = 2.7 × 10 3 N × 50 × 10 - 3 M = 135 J (3) times of gas to piston in 1 minute: n = 1800 / 2 = 900 power of gasoline engine: P = wtotal / T

A problem about the principle of addition and multiplication
There are three passageways in the South and two passageways in the north of a building. How many ways can someone go from one passageway to another?

The first step is to choose whether to enter from the South or the north. This is the principle of addition. There are three channels to enter from the South and two channels to enter from the north. There are five choices
The second step is to select the exit. If one of the five channels has been selected, you have to select one exit from the remaining four channels
Step one, step two, this is the principle of multiplication: 4 * 5 = 20
Principle of addition: to do a thing, there are n kinds of methods to complete it, just like choosing import, there are 2 kinds: South and North. There are 3 methods in the South and 2 methods in the north, so there are 5 methods to choose
Multiplication principle: to do a thing, it needs to be divided into N steps, just like the first and second steps above. There are 5 different methods to do the first step, and 4 different methods to do the second step. The total method is 5 * 4 = 20

To solve the differential equation DX: dy + YX = 0, satisfy y} x = 1 = 1

dy/dx=-x²y
=>dy/y=-x²dx
=>lnlyl=-(1/3)(x³)+c1
And x = 1, y = 1
=>c1=-1
=>y=±e^[-(1/3)(x³)]

720 cubic decimeter = () cubic meter 2500 cubic cm = () cubic decimeter

0.72
two point five

Integral multiplication and factorization
By this (X-Y) ^ 2-2 (X-Y) * (1 / 2) + (1 / 2) ^ 2 = 0
How can we get to this X-Y = 1 / 2 (1)

(x-y)^2-2(x-y)*(1/2)+(1/2)^2=0
(x-y-1/2)^2=0
x-y-1/2=0
x-y=1/2

Find the tangent plane equation and normal equation of the point m (1,2,3) on the elliptic surface x ^ 2 / 3 + y ^ 2 / 12 + Z ^ 2 / 27 = 1

∵Z=2x^2+y^2
∴Zx'│m=4,Zy'=-2
The normal vector of the tangent plane is (4, - 2, - 1)
So the tangent plane equation is 4 (x-1) - 2 (y + 1) - (Z-3) = 0, that is 4x-2y-z = 3
The normal equation is (x-1) / 4 = (y + 1) / (- 2) = (Z-3) / (- 1)

How many miles does the 100 meter world record equate to a car? (km / h)
If I run ten seconds, I'm 36 kilometers per hour
But no one ran 7 seconds, that speed, should be 51 kilometers per hour
What I want to know is how fast can a man reach in an instant when he runs 100 meters?
Because people start from scratch when they run 100 meters
And if a BYD fo car is allowed to run 100 meters with bolt, who can get to the finish line first?
Can bolt catch up with the car when it is running 60 miles? (consider instantaneous speed)

=3600*100/9.72
=37 km / h