9 math problems urgent . Please, big brothers and sisters!

There are several discrepancies in the questions he did, all of them wrong, look at me!! Can you understand.

1.Save tons per day, save 28 * tons per day in 28 days, you can burn 2 more days, 28 + 2 = 30 days.

2.(when the length that has been repaired accounts for 4 7 of the total length) the road length is x, then the one that has been repaired is 3 x 8 meters, and then 55 meters is repaired to account for the total length of 4 7, so 3 x 8 + 55 = 4 x 7, the solution is x = 280 meters.

3.Because it takes 10 minutes for Xiao Ming to go from A to B, and when they meet in 6 minutes, it will take 4 minutes for Xiao Ming to get to B, so Xiao Hong took 6 minutes to walk Xiao Ming's 4-minute journey, so Xiao Hongdao A takes a total of 6 4 * 10 = 15 minutes, so it takes 15-6 = 9 minutes.

4.Male x people, female 570-x people, x * (1 + 1 6) + (570 - x) (1-1 5) = 610 x = 420 , 570 - x = 150 420 boys, 150 girls.

3) I don't know how to calculate this -2*996+1993=1

7.（1）x=50

2）x=6800

3) x=9, two more faces 2*1 6=1 3

.5*28 (days.)

2. Solution: If x meters have been repaired, then 5 3x meters have not been repaired.

x+55=4/7*8/3x

x=105m

8/3x=280m

A: The total length is 280m

3. Xiao Ming walks 1 10 per minute on this road

1-6*1 10) 10=2 25 The distance taken by Xiaohong per minute accounts for the length of this road.

1 2 25 = minutes.

Answer: Minutes. 4. If there are x males in the first semester, there will be (570-x) females.

116%x+85%(570-x)=610

665÷7=95

So the passenger car travels 50 kilometers per hour.

Set the speed of the bus to x kilometers per hour.

1+9/10)x*7=665

x=50 then the passenger car travels 50 kilometers per hour.

Solution: If the passenger car travels x kilometers per hour, then the truck travels 9 10x kilometers per hour, 7 (x+9 10x) = 665

Solution: x=50

That is, the passenger car travels 50 kilometers per hour.

Speed sum is: 665 7 = 95 km h.

The speed of the bus is: 95 (1+9 10)=50 km/h.

Customer) t+v (customer) t=665 solution v (customer) = 95 v (cargo) = (kilometers per hour).

Equation Method:

Solution: If the passenger car travels x kilometers per hour, then the train travels 9x 10 kilometers per hour (9x 10 + x) 7=665

19x/10=95

x =95× 10/19

x = 50 A: The passenger car travels 50 kilometers per hour.

You don't care about repetition, add up the people who get it wrong: 4 + 6 + 10 + 20 + 39 = 79 and then use 52 * 5 = 260....This is if all pairs are used to subtract the error in the whole pair:

260-79=181 is actually right 181181 minus 7 people who only got one question right, and 6 people who were all right (6*5=30), which is 181-7-30=144

The remainder is 52-7-6 = 39 (people).

Put the person who does 2 questions correctly and the person who gets 3 questions right"All in one"and think of them as the ones who do the 5 questions right, because they have the same number of people.

There are x people who set 2 questions right.

5x+(39-2x)*4=144

5x+156-8x=144

3x=-12

x=4, so the people who do 2 questions correctly and those who do 3 questions correctly are 4 people, so the people who do 4 questions correctly are: 39-8=31 (people) Finally, 31*4+4*5+30+7=181 is exactly the right quantity.

I'm going to make it very clear here, you don't have to write it that clearly.

Answer: The number of people who got 4 questions right is 31.

The total number of questions is 52*5=260.

There are 4 + 6 + 10 + 20 + 39 = 79 wrong questions.

The correct questions are: 260-79=181 questions.

6 people in full pairs, a total of 5*6=30 questions.

For 7 people in 1 question, a total of 1*7=7 questions.

The remainder: 52-6-7 = 39.

Number of correct answers remaining: 181-30-7=144 questions.

If there are x people for two or three questions, then there are 39-2x people for 4 questions, 2x+3x+4(39-2x)=144

x=439-2x=39-8=31 people.

Answer: A total of 31 people got 4 questions right.

Add up the number of people who got each question right, i.e. how many questions were correct. 48+46+42+32+13=181

This number is the sum of the questions that each person has corrected: 7 people who have got one question right, those who have done the second and third questions correctly are x, those who have 4 questions correctly are y, and those who have 5 questions correctly are 6List the system of equations:

7+2x+3x+4y+5*6=181, 7+2x+y+6=52

The number of people who solve x=4 y=31 and get 4 questions right is 31.

4 + 6 + 10 + 20 + 39 = 79 (person).

However, there are 79 people, and there are 7 people who know that they only do 1 question correctly, and there are still more than 52 people who use 79-7=71 (people), and they also know that all 6 people are right.

71-6=65 (person).

Next, use the equation) x is the person who does 4 questions right, y is the person who gets 2 and 3 questions right, x+y=52

52/y=26

26-x=18

52-(18*2)=16 (person).

There were 16 people who got 4 questions right.

Solution: Question 1:

999 and 8/9 (—1 and 1/9).

Question 2: A-2|+(b+1)²=0

a-2|≥0，(b+1)²≥0

a=2，b=-1

b = 1a + b 15 thanks.

Question 1:

Question 2: 1)|a-2|+(b+1)2=0

a-2|=0，(b+1)2=0

A=2, b=-1

i.e. b2 = 12) a3 + b 15

(1) (a+b)*=a*+2ab+b*=4, because ab=1, so a*+b*=2

Because (a-b)*=a*-2ab+b*=2-2=0(2) because (a+1 a)*=a*+2+(1 a)*=9, a*+1 a*=9-2=7

The solution is as follows: (Note: Multiplication with crosses).

The first floor gives the matching method.

Question 2 :(x-1)(x+2)(x-3)(x+4)+24=(x +x-2)(x +x-12)+24=(x +x) -12(x +x)-2(x +x)+24+24=(x +x) -14(x +x)+48

x²+x-6)(x²+x-8)

x+3)(x-2)(x²+x-8)

Question 3: Easy to obtain: (x+5y) square = 1 and multiply x on both sides at the same time to get x square plus 5xy equals x

To the right, simplify x to the third power + 5x squared y + x squared = x (x square + 5xy + x) = x (x + x) = 2x squared.