If the speed of the car from a to B is 5 km slower than the scheduled time per hour, the time of arrival will be one eighth longer than the scheduled time; if the speed is one third higher than the scheduled time, the time of arrival can be 2 hours earlier than the scheduled time, and the distance between a and B can be calculated

According to the formula: distance = speed times time, we should calculate the predetermined time and speed first
Because when the speed is slow by 5km, the arrival speed is 9 / 8 of the original speed. According to the formula, the speed is 8 / 9 of the original speed, that is, 5km is 1 / 9 of the predetermined speed, and the predetermined speed is 45 (km / h);
Similarly, the scheduled time is 8 hours
AB distance = 45 times 8 = 360 (km)
Is the square of a + AB + AB = the square of a + 2Ab a multiplication formula
Square of a + AB + AB = square of a + 2Ab
This step is called "merging the same type"
This conclusion can be obtained by multiplicative allocation
Merge 2Ab + AB from the left to the right
According to the rule of merging similar terms: coefficient addition and subtraction as coefficients, the index of letters and letters remain unchanged
For example: 2XY + 5xy = (2 + 5) xy = 7xy
The solution of the equation 4x2m = 3x + 1 is the same as that of the equation 3x2m = 4x + 1
Equation 4x + 2m = 3x + 1
The solution is x = 1-2m;
Equation 3x + 2m = 4x + 1
The solution is x = 2m-1;
So 1-2m = 2m-1,
And M = 0.5,
The solution of the equation is x = 0
If the length and width of a rectangle increase by 2 cm, the area of the new rectangle will be 32 square cm larger than that of the original rectangle. What is the circumference of the original rectangle?
And ask for explanation
sos!
teacher:
If the length and width of the original rectangle are a and B, then the original area = AB and the area of the new rectangle = (a + 2) (B + 2) the known condition 2. The area of the new rectangle is 32 square centimeters larger than that of the original rectangle, that is, (a + 2) (B + 2) - AB = 32
The square of a - the square of B / the square of a - AB / (a + 2Ab + the square of B / a)
Where a = 2, B = - 1
The square of a - the square of B / the square of a - AB / (a + 2Ab + the square of B / a)
=（a+b）(a-b)/a(a-b)÷(a+b)²/a
=1/(a+b)
=1/(2-1)
=1
If you don't understand this question, you can ask. If you are satisfied, please click "select as satisfactory answer"
By adding () to both sides of the equation x + 4 = 6-3x, we can get the equation 4x-2
By adding (3x-4) to both sides of equation x + 4 = 6-3x, equation 4x-2 can be obtained
Math problem solving formula, urgent! Urgent!
Arrange 1, 2, 3,..., 20042005 in the following position (horizontal is "line")
1 8 9 16 17 24→↓ ↑ →↓
2 7 10 15 18 23 ↓ ↑ ...
3 6 11 14 19 22↓ ↑...
So, 2005 should be the number () in the () line
This is actually very simple. If you look at it in two columns, there are eight numbers. 2005 △ 8 = 250 + 5
Since 5 is greater than 4 in each column, the number of columns in 2005 is 250 × 2 + 2 = 502
Looking at the number of rows, it's obvious that the last few numbers are arranged in the same order
2000 2001 2008
1999 2002 2007
2003 2006
2004 2005
So 2005 is the number 502 in line 4
Number 502 in line 4
Line 4, column 501
Just April 2005
4，252
First simplify and then evaluate: (AAB − B2 − Ba2 − AB) / (1 + A2 + b22ab), where a = - 1 + 3, B = - 1-3
The original formula = [AB (a − b) − BA (a − b)] / / 2Ab + A2 + b22ab = A2 − b2ab (a − b) · 2Ab (a + b) 2 (2 points) = (a + b) (a − b) AB (a − b) · 2Ab (a + b) 2 = 2A + B (4 points) when a = - 1 + 3, B = - 1-3, the original formula = 2 − 2 = - 1. (6 points)
14 * (2 + 3x) = 42
Hello! 14 * (2 + 3x) = 4214 * 2 + 14 * 3x = 42 28 + 14 * 3x = 42 14 * 3x = 42-28 14 * 3x = 14 3x = 14 △ 14 3x = 1 x
Solution: 2 + 3x = 42 △ 14
3x=3-2
x=1÷3
x=1/3
14*(2+3x)=42
2+3x=42÷14
2+3x=3
3x=3-2
3x=1
x=1÷3
X = 1 / 3
I wish you progress in your study, you can ask if you don't understand! thank you!!
Urgent! Find 1 interesting D math problem!
Demand interesting D
It's better to have an answer!
1. Crossing the bridge
Today, there are four people who have to walk from the left side of the bridge to the right side in the evening. The bridge can only walk for two people at a time, and there is only one flashlight. When crossing the bridge, you must use a flashlight. The fastest time for four people to cross the bridge is as follows: a 2; B 3; C 8; D 10. The fast one has to wait for the slow one. How can we get all the people to cross the bridge at 21?
2. Insert numbers skillfully
125 × 4 × 3 = 2000, this formula is obviously different, but if two numbers "7" are inserted into the formula skillfully, this equation can be established. Do you know where the two numbers "7" should be inserted?
3. Warm seasons
Spring summer × autumn winter = spring summer autumn winter
Spring winter × autumn summer = spring summer autumn winter
In the formula, spring, summer, autumn and winter each represent four different numbers. Can you point out what they represent?
4. The broken car went down the mountain
An old car has to walk two miles, one mile up and one mile down the hill. When it goes up the hill, its average speed is 15 miles per hour. How fast can it reach the average speed of 30 miles per hour when it goes down the hill for the second mile? Is it 45 miles? You have to think it over!
5. How many eggs do you sell
Old lady Wang goes to the market to sell eggs. The first person buys half and one of the eggs in the blue box. The second person buys half and one of the remaining eggs. At this time, there is still one egg left in the blue box. How many eggs does old lady Wang sell?
6. How many people take the exam
There are six multiple-choice questions on the test paper, and each question has three options. As a result, the marking teacher found that there are different choices for each of the three papers. How many people participated in the test at most?
answer
First, a and B cross the bridge together, then B stays on the other side, and a returns alone. After a returns, a gives the flashlight to C and D, and C and D cross the bridge together. After C and D arrive on the other side, C gives the flashlight to B, and B brings it back. Finally, a and B cross the bridge together again. The required time is: 3 + 2 + 10 + 3 + 3 = 21 minutes
2 the formula after inserting numbers is: 1725 × 4 × 3 = 20700
Summer spring = 2; winter autumn = 8
In any case, the average speed of a broken car can't reach 30 mph, because when the average speed is 30 mph, the total time for a broken car to go up and down the mountain should be 1 / 15 hour, and it takes 1 / 15 hour for a broken car to go up the mountain. So the average speed of a broken car can't reach 30 mph
Mrs. Wang sold 10 eggs in total
6 up to 13 participants
1. How old is little smart
An uncle asked "smart" how old he was. He said: "if you subtract two times my age three years ago from two times my age three years later, it will be equal to my age now."
How old are you this year?
2. True and false silver dollar
A businessman had nine silver dollars, one of which was a lighter fake one. Can you find out the fake silver dollar by weighing it twice with a balance?
The answer is:
He is older three years later than three years ago
1. How old is little smart
An uncle asked "smart" how old he was. He said: "if you subtract two times my age three years ago from two times my age three years later, it will be equal to my age now."
How old is "smart" this year?
2. True and false silver dollar
A businessman had nine silver dollars, one of which was a lighter fake one. Can you find out the fake silver dollar by weighing it twice with a balance?
The answer is:
1. His age after three years is 3 + 3 = 6 years older than that of three years ago. The difference between his age after three years and that of three years ago is 6 × 2 = 12 years old, which is equal to the present age of "little smart". So the age of "little smart" is: (3 + 3) × 2 = 12.
2. Divide the silver coins into three groups, three in each group.
For the first time, put the two groups in the two plates of the balance. If the balance is uneven, then the false silver is in the light group. If the balance is in balance, then the false silver is in the third group.
The second time you weigh the group with fake silver yuan, you can take 2 pieces at will and put them in two plates respectively. If the balance is uneven, the fake silver yuan is the light one. If both ends of the balance are balanced, the last one is the false silver dollar. Put it away
There are (7) monkeys riding on the tree and one crouching on the ground. How many monkeys are there in all? Ha ha!
There are 27 pearls, one of which is fake, but its appearance is the same as the real one, but it is lighter than the real one. Q: can you find the fake pearl by weighing it with a balance at least several times (no brick code)? Take one and put 13 on both sides. If it is balanced, it will be false, that is, once; if it is unbalanced, it will be false, that is, once; if it is unbalanced, it will be false, that is, twice; if it is unbalanced, it will be false, that is, once; if it is unbalanced, it will be false, that is, once; if it is unbalanced, it will be false, that is, once; if it is unbalanced, it will be false, that is, once; if it is unbalanced, it will be false, that is, once; if it is unbalanced, it will be false, that is, once; if it is unbalanced, it will be false Two, if balanced, the last... Unfold
It's not necessary to use a balance to weigh a pearl, but it's lighter than a real one? Take one and put 13 on both sides. If it is balanced, it will be false, that is, once; if it is unbalanced, it will be false, that is, once; if it is unbalanced, it will be false, that is, twice; if it is unbalanced, it will be false, that is, once; if it is unbalanced, it will be false, that is, once; if it is unbalanced, it will be false, that is, once; if it is unbalanced, it will be false, that is, once; if it is unbalanced, it will be false, that is, once; if it is unbalanced, it will be false, that is, once; if it is unbalanced, it will be false Two, if balanced, the last time taken out is false (a total of four times), if unbalanced, the light one is false. (5 times in total) put away

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