Junior 2 math problems, urgent! Mathematics in the second year of junior high school is urgent!

Question 1: x y) 2 = x2 2 x y y2 = 9 1 formula.

x y) 2=x2 2xy y2=5 2.

From (1 formula 2): (x2+2xy+y2) (x2-2xy+y2)=4xy=(9-5)=4

i.e. xy=1 second question: (x y 1) (x y 1) x (y 1) x (y 1).

According to the squared difference formula: (a b) (a b) a2 b2 x (y 1) x (y 1) x2 (y 1)2 i.e. a is equivalent to x and b is equivalent to y 1).

Because (x+y) 2=9, so x 2+2xy+y 2=9, (1) because (x-y) 2=5, so x 2-2xy+y 2=5, (2) so (1)-(2)4xy=4, so xy=1;

x+y-1）*（x-y+1）

x-(y-1)][x+(y-1)]

x^2-(y-1)^2

x^2-(y^2-2y+1)

x^2-y^2+2y-1.

Because the square of (x+y) = 9

So x 2 + 2 x y + y 2 = 9

Because the square of (x-y) = 5

So the square of x - 2xy + the square of y = 5

So 4xy=4

So xy=1;

x+y-1）*（x-y+1）

x+(y-1)][x-(y-1)]

x^2-(y-1)^2]

x^2-(y^2-2y+1)]

y^2-x^2+2y-1

x+y) = 9

x square + y square + 2xy = 9 --

x-y) = 5

x square + y square - 2xy = 5 --

4xy=4xy=1

Question 2. If yes (x-y+10).

Should. [x+(y-10)]*x-(y-10)]=square of x-squared (y-10)=x-y+10

If that's right, I didn't come up with it.

Because the square of (x+y) - the square of (x-y) = 4xy, 4xy = 9-5 = 4

So xy=1;

This is a test of your mastery of the perfect square formula!

xy=1 because the square of (x+y) - the square of (x-y) = 4xy = 4

There is an error in 2 questions.

Positive solution, standard x = 14, interpreted as 39 yuan.

My equation is 25 + 1053 x = 378 x I don't know if it's true or not.

Is it correct to set the "standard" to x, if so.

With arithmetic methods: the number of teachers = (1053-378) 25 = 27 (people) standard unit price = 378 27 = 14 (yuan).

Interpretation unit price = 1053 27 = 39 (yuan).

Use the equation: Let the number of teachers be x

then 25x=1053-378

Just follow the above arithmetic method to continue the calculation...

Finally, I would like to say that I did not understand the equations you listed.

Yes, this is the column formula, find x=14, "standard" is 14 yuan, "interpretation" is 14 + 25 = 39 yuan.

Isosceles right triangle can be seen by drawing.

The area is 5*5 2=

I don't want to do it... What is your AF.

Upstairs wrong.

1) Because dab= aob= abo, ac bisects dab, so cab=1/2 aob+1/2 abo=45 degrees + abf, so fab=180 degrees-45 degrees- abf=135 degrees- abf, so afb=180 degrees-135 degrees- abf+ abf=45 degrees.

2) Not true because the AOB degree is not known.

Proof: DBA= EBC=60 degrees, then DBE= ABC

db=ab, eb=bc, then dbe abc(sas), de=ac=af;

The same can be proven: ECF BCA, EF=AB=AD

Therefore, the quadrilateral ADEF is a flat-curved quadrilateral.

Proof DBA= EBC=60 degrees.

then DBE= ABC

db=ab eb=bc

then dbe abc (sas).

de=ac=af

The same goes for it. ECF rough BCA

ef=ab=ad

The sun sold is a parallelogram with a curved chain quadrilateral ADEF.