Everyone helped me do a few math problems, and there was a big reward

1, ①3x²-2y²+(y²-2x²)-6x²-y²)=-5x²

When x=-2, the original formula =-20

2(2x³-6x-4)-3(x³+x²-2x-3)=x³-3x²-6x+1

When x=-2 3, the original = -8 27- 4 3+4+1=-91 27

2. (4a-5b-ab)-(2a-7b+5ab)=2a+2b-6ab=2(a+b)-6ab

When a+b=2, ab=-1, the original formula=4+6=10

3. (2x^2+ax-y+6)-(abx^2-3x+5y-1)=(2-ab)x²+(a+3)x-6y+7

Since the equation is independent of x, 2-ab=0, and a+3=0, so a=-3, b=-2 3

So 1 2a -2b + 4ab = 1 18 + 4 3 + 8 = 169 18

If it is 1 2 a -2b + 4ab =

The answer is uncertain, but the accuracy rate is okay.

3x 2-2y 2+(y 2-2x 2)-(6x 2-y 2), where x = -2, y = 3

3x 2-2y 2+y 2-2x 2-6x 2+y 2,-5x 2 when x=-2,y=3Time.

Original = (-5) * (2).

2 (2 x 3-6x-4) -3 (x 3 + x 2-2x-3), where x = -2 3

4x^3+12x-8-3-3x^3-3x^2+6x+6x^3-6x-2-3x^2

When x = -2 3, the original formula = -8 27 + 2 3-2 = 12 274a-5b-ab)-(2a-7b+5ab)4a-5b-ab-2a+7b-5ab

2a+2b-6ab

When a+b=2, ab=-1, the original formula =2(a+b)-6ab

It's too little, you can keep it for yourself.

I'll try to do it.

1.Assuming that the original stock of A is 1, then A is 1 plus;

A = is the share B sold later, then the original B is a plus (a multiplied;

A share is profitable, and B shares are loss.

A share is profitable, and B shares are loss.

Therefore, B loses and A makes a profit. It's a loss!

2.Solution: If the face value of 60 points is x, then the face value of 80 points is 20-x pieces, column:

13 yuan 6 jiao = 1360 points.

60x+80(20-x)=1360

60x+1600-80x=1360

20x=240

x=1220-x=8

Answer: Bingbing buys 12 stamps with a face value of 60 cents and 8 stamps with a face value of 80 cents.

3.If X wins, it will be 11-x

According to the title: 3x+11-x=23

Solution x=11

Solid wins 6 games, draw 5

4.Set the cost to x

The original price is: x+25%x

The discounted pricing is: x+10%x

Discount=(x+10%x) (x+25%x)==

So it's 88% off.

5.Well depth x m

3(x-4)=2（x+5)

x=22 rope length 54 m

6.Set up Xiao Zhang's house to the railway station is x kilometers.

x 30-15 60 = x 2 30 + x 2 60x = 30 km.

A: Xiao Zhang's house is 30 kilometers from the railway station.

It's finally done

1.The cost of A is: a (1 + 20%) = 5 6 a The cost of B is: a (1-20%) = 5 4a

Total cost: 5 6a + 5 4a = 25 12a

Total revenue: 2a

25/12a＞2a

So it's a loss. Total loss: 25 12a-2a = 1 12a yuan 6 jiao = 1360 points.

Solution: If the face value of 80 cents buys x pieces, then the face value of 60 cents buys 20-x pieces 80x+60(20-x)=1360

80x+1200-60x=1360

20x=1360-1200

20x=160

x=820-x=20-8=12

Answer: I bought 12 pieces with a face value of 60 points, and bought 8 pieces with a face value of 60 pointsSolution: Suppose the team wins x games, then draws 11-x games.

3x+（11-x）=23

3x+11-x=23

2x=23-11

2x=12x=6A: The team has won 6 games.

4.Solution: Set the discount to x

1+25%）*x=1+10%

x = A: 88% off**.

5.Solution: Set the depth of the dry well to be x meters.

4（x+3)=5（x+1)

4x+12=5x+5

5x-4x=12-5

x=7A: The depth of the dry well is 7 meters.

6.Solution: Let Xiao Zhang's house go to the railway station 2x kilometers (set 2x for the convenience of calculation) 2x 30 = x 30 + x (30 2) + 15 60x 15 = x 30 + x 60 + 1 4

x(1/15-1/30-1/60)=1/4x*1/60=1/4

x=1/4*60

x=152x=2×15=30

A: The distance from Xiao Zhang's house to the railway station is 30 kilometers.

1. The original price of type A is X yuan, the original price of type B is y yuan, x*(1+20%)=a, Y*(1-20%)=a, and the solution is obtained, x=a, y=a, 2a-(a, so the loss is 12 yuan.

2. If you buy 60 cents face value stamps x pieces, then buy 80 cents face value stamps (20-x), and solve it, x = 12, then, 60 points face value 12 pieces, 80 points face value 8 pieces.

3. If you win x games, you will draw (11-x) games, 3x+11-x=23, and if you win, x=6, you will win 6 games and draw 5 games.

4. Set the original price of x yuan, the selling price is x* (1 + 25%), and the discounted price is x* (1 + 10%), x (1 + 10%) x (1 + 25%) =, therefore, discount**.

5. Set the depth of the well x meters, (x+3)*4=(x+1)*5, solve x=7, and the depth of the well is 7 meters.

6. The time for taking a taxi is x hours, 15 minutes = hours, 30 * 2 * x = 30 * (x +, solution x =, then the distance between Xiao Zhang's house and the railway station is 2 * [kilometers).

1. The ratio of time required for the complete journey of passenger cars and trucks is 18:27=2:3, so the speed ratio is 3:2

That is, the distance ratio of the two cars at the time of meeting is 3:2

Then the passenger car traveled: 810 [3 (2+3)]=486 (km) and the truck traveled: 810 [2 (2+3)]=324 (km) or 810-486=324 (km).

2. Solution: If there are x at the top, then Ningning will have (270-x), and 25%x+270-x=(270-x)(1+20%)x=120 according to the title

So 270-x=270-120=150

A: There were originally 120 at the top and 150 at Ningning.

3. Solution: Let the cost of this commodity be x, according to the topic.

1+20%)x×80%=x-64

x=1600

A: The cost of this product is 1600 yuan.

1. Calculate the speed of buses and trucks first.

Passenger car speed = 810 18 = 45km h

Truck speed = 810 27 = 30km h

Let the passenger car travel x kilometers and the truck Y kilometers, and the time of the two vehicles is the same x+y=810;

x/45=y/27；

2. Set x tops and Y Ningning.

x+y=270;

x*25%+y=(1+20%)y

3. The cost is x

1+20%）x*80%=x-64;

Solution: From the square root of x-2 is 2 to get x-2=4, we get x=6. The cube root of 2x+y+7 is 3, and 19+y=27, so y=8then x +y = 100 and its square root = +10 or -10

The two square roots of a are x y, so x=-y, and the second equation is substituted, y=-2, x=2, so the square of a=x or the square of y, which is 4.

In the first question, the square root of x=6, y=8, and x +y is 10;In the second problem, because x,y is the square root of a, x,y are opposite numbers to each other, that is, x=-y, and substituting the equation to get x=2 and y=-2.

What grade are you in, you don't use your brains, and the reward is too small, so you don't want to do it.

Hurry up with your homework, girl.

The bounty is too small to be done.

What grade are you in? Don't use your own brains.

1.The following graph, which cannot be obtained by cutting the cube, is (no answer) aTriangle bSquare cTrapezoidal DParallelogram.

The square is also a parallelogram.

2.In order to solve the problem of excessive drug quality, a province decided to greatly reduce the price of drugs, and reduced the price of a common drug with an original price of 49 yuan by 30%, then the price after the price reduction is (c).

Yuan Yuan Yuan.

The first question is not required to cut it, otherwise all four shapes can be obtained.

2. Select C