What are the respective answers to questions 6 8 9

6, a recognized answer 8, hint is the hint text attribute d 9, d is the wrong attribute written error (8, they say b is the attribute of filling in the text, is it text or number, or password these attributes).

Question 1 A, 2nd C, 3rd D

Why not use a question search software?

Exercise (2) x=48 55

y=11/4 y=-(28/55)

Let the average speed of the aircraft be x km h and the wind speed be y km h

10/3)(x-y)=1200

5/2)(x+y)=1200

Solve this system of equations and get: x=420

y=60A: The average speed of the aircraft is 420 km h, and the wind speed is 60 km h

Suppose the average speed of this army on the first day of march is x km h, and the average speed of the second day is y km h, according to the title, get: 4x+5y=98

5y-4x=2 ②

Solve this system of equations and get: x=12

y=10A: The average speed of this army on the first day of march was 12 km h, and the average speed on the second day was .

10km/h

Set up x sheets of paper to make the box body, Y sheets of paper to make the bottom of the box, so that the box body and the bottom of the box are just matched. According to the question.

Meaning, get: x+y=36

2 25x=40y Caution.

Solve this system of equations and get: x=16

y=20A: Use 16 pieces of iron sheet to make the box body, 20 pieces of iron sheet to make the bottom of the box, you can make the box body and the bottom of the box just match or filial piety.

Set a large car can transport x tons of goods at a time, and a small car can transport y tons of goods at a time, according to the question.

Meaning: 2x+3y=

5x+6y=35 Solve this system of equations and get: x=4

y=5 2So, 3x+5y=3 4+5 (5 2)=tons.

A: 3 large carts and 5 small carts can transport tons of goods at one time.

Set the slope road distance to x km and the flat road distance to y km, according to the title, get:

x/3+y/4=54/60 ①

y/4+x/5=2/60 ②

Solve this system of equations and get: x=

y=A: The whole journey from A to B is.

Suppose you need to take 30% and 75% of the medicine x kg, y kg, according to the title, get:

x+y=18

30%x+75%y=18×50%

Solve this system of equations and get: x=10

y=8A: 10kg of potion containing 30% of the medicine and 8kg of potion containing 75% of the medicine need to be taken

Set the unit price of A product before the discount is X yuan, and B product is Y yuan

60x+30y=1080 ①

50x+10y=840 ②

Solve this system of equations and get: x=16

y=4So, 500 16+500 4-9600=400 (yuan).

A: It costs 400 yuan less than no discount.

Wrong. The reason is as follows: set the ** of a toothpaste for X yuan, and the ** of a shirt orange toothpaste for Y yuan.

According to the title, it gets: 39x+21y=396, that is: 13x+7y=132, so.

52x+28y=39x+21y+13x+7y=396+132=528 (yuan).

Because 518≠528, this record is incorrect.

DCBBAC 7 problem A is a parallel to the x-axis straight line, called the parabola at the D option point 8, the value of question 1 is 32 triangles; (Let y x=ky=kx draw the row domain to find the intersection of y=kx and the row domain k value 9 question a 2=1, c 2=m+1, e 2=m+1 2, so m 1.)

Similar to simple calculation problems.

Solution: Four rules of operation (calculated in order, multiplication and division first, then addition and subtraction, parentheses are counted first, and power is calculated first), that is, the off-form operation (recursive equality calculation) needs to be carried out under the premise of this principle. Problem solving process:

Extended data [calculation result]: first align the last digit of the two multipliers, and then use the second multiplier respectively, multiply a multiplier for each digit from the last digit in turn, and finally add up the calculated result to be the product, if the multiplier is a decimal place, you can first expand it by the corresponding multiple, and finally the product is narrowed by the corresponding multiple;

Problem solving: Step 1: 0 88=0

Step 2: 1 88 = 880

According to the above calculation steps, the combination result is moved to the left, and the decimal point product is 88, please ask if you have any doubts, and you are satisfied.

6,3* cubic meters.

8, cubic meters.

9,3*2*4=24 cubic meters.

Set of formulas for multiplying the base area by the height

6. Protective gas, because nitrogen is an inert gas and is chemically inactive.

7. Helium, neon, argon, krypton, xenon, inert gas, shielding gas, 8. I don't know if there are words behind the horizontal line. This tip is too little.

9. Improve the environmental situation, use clean energy, and actively plant trees, afforestation, grass, etc.

Such a simple topic. It is the basic knowledge of the first volume of junior high school chemistry. And there is a summary of the knowledge points at the end of each unit. Go and flip through it yourself, it's more helpful to remember.