Does anyone know this question, I hope to talk about it in detail

Solution: Using the formula: a 2-b 2 = (a + b) (a - b) a 3-b 3 = (a - b) (a 2 + ab + b 2).

Because: x x+x y=x( x+ y) xy-y 2=y(x-y)=y[( x) 2-( y) 2]=y( x- y)( x+ y).

So: (x x+x y) (xy-y 2)=[x( x+ y)] y( x- y)( x+ y)=x y( x- y).

Because: x+ (xy)+y=( x) 2+ x y+( y) 2

x√x-y√y=(√x)^3-(√y)^3=(√x-√y)[(x)^2+√x√y+(√y)^2]

So: (x+ xy+y) (x x-y y)=[( x) 2+ x y+( y) 2] ( x- y)[(x) 2+ x y+( y) 2]=1 ( x- y)

So the primitive x y( x- y)-1 ( x- y)=x y( x- y)-y y( x- y)=(x-y) y( x- y).

x+√y)(√x-√y)/y(√x-√y)

x+√y)/y

To be noted beforehand, here the numbers are indicated by the letters after the exponents.

Let's start with the numerator of the first polynomial: x x+x y, and you can see that the common factor of these two mononomials, x, extraction, is x( x+y).

Now let's take a look at the denominator: xy-y2, the common factor is y, reduced to y(x-y) Now it's time for the numerator of the second polynomial: x+ xy+y, which can become x2+ xy+ y2, which is the perfect square formula, which can become (x+ y)2

Denominator: Cannot be simplified.

But we must remember what Mr. la said - the denominator cannot have a root number, so the upper and lower multiplication x+ y, so it becomes (x+ y)3 x2-y2

In this way, the formula becomes:

x(√x+√y) (x+√y)3

y(x-y) x2-y2

And then it's distracted.

The maximum value of the quadratic function in the open interval is the point where its axis of symmetry is located, and the open interval is the kind without the end of the interval, and in the case of only giving the function two zeros, because the quadratic function is symmetrical with the axis of symmetry, the abscissa of the axis of symmetry is equal to the abscissa of the midpoint of the two zeros, which is easy to understand, the axis of symmetry of the function is x=(-1+3) 2=1

Knowing the two, then the coordinates of the symmetry axis of the quadratic function are x=1, that is, when x=1, the function has a minimum value of -8, and then these conditions can be set into the options to filter the answers.

Written by the computer, it's not good-looking, forgive me (you can ask if you don't understand).

How many euros is R3, it's too far to see clearly.

a-b-c is equivalent to a-(b+c).

Because the triangle must be greater than the sum of the two sides, so a+b-c>0 and a-b-c<0

So this point is in the fourth quadrant.

For triangles with three sides long a, b, c, there are.

a+b>c

a+c>b

b+c>a

Therefore, the shift gives a+b-c>0, a-b-c<0, that is, x>0, y<0, which is the fourth quadrant.

Thanks for the reminder, corrected).

The three sides of the triangle a+b-c must be greater than 0 and a-b-c must be less than 0

x>0,y<0 in the fourth quadrant.

If the police car and the drug trafficking vehicle arrive at place B at the same time, the problem can be solved.

The speed of the police car and the drug trafficking car is 4x and 3x km/h, respectively, and the equation 360 (3x)-360 (4x)=, is established, and the solution is x=24. So, the speed of a police car and a drug trafficking vehicle is one kilometer per hour.

For example, how fast does a police car have to be to catch up with a drug trafficking car before the delivery of the poisoned rice?

1. The police car should catch up with the drug trafficking vehicle before picking up the goods, so the police car and the drug trafficking car should arrive at place B at the same time.

2. Set the speed of the police car to x, the drug trafficking car to be 3 4x, and the running time of the police car is txt=(t+

t = hours. x=96 (police car).

3 4x = 72 (drug cart).

Calculate the unit price of each fruit first, and then compare it.

D should be selected.

Analysis: In the beginning, the egg floats on the surface of the salt water, at which point buoyancy = gravity.

When water is added slowly, the density of the brine gradually decreases, and the egg slowly sinks and submerges, indicating that the buoyancy changes from constant to gradually decreasing in this process. The buoyancy does not change before submersion, so the curve begins to have a horizontal segment.

When the egg sinks to the bottom, the buoyancy does not decrease.

d. Before the egg reaches the surface, buoyancy is always equal to gravity; After submerging into the water, the buoyancy is equal to the weight of the discharged salt water, but the density of the salt water is gradually decreasing, tending to the density of clear water, and thus the buoyancy is also gradually decreasing to the weight of the water that tends to be the size of the egg.

The buoyancy remains constant until it floats to sinking, and when it begins to sink, the buoyancy decreases, but does not fall.