2. A mountain road, from the foot of the mountain to the top of the mountain, takes less 1 hour to be 1 km, and from the top of the mountain to the foot of the mountain, it can be completed in 50 minutes. It is known that the downhill speed is 1.5 times of the uphill speed. What are the downhill speed and uphill speed, and how many kilometers is the one-way street?
Someone took part in the 3000-meter race. After running a distance at a speed of 6 meters per second, he ran the rest at a speed of 4 meters per second. How many meters did he run in a *** 10 minute at a speed of 6 meters per second?
Last year, Party A and Party B sold12,200 pairs of shoes. This year, Party A sold 6% more than last year and Party B sold 5% less than last year. The total cutting amount of the two kinds of shoes has increased by 50 pairs. How many pairs of shoes did Party A and Party B sell last year?
5. If the equation about x mx+3xx+5x-nxx+3=3, what are the values of m and n respectively?
6. It is known that three nonnegative numbers A, B and C satisfy 3a+2b+c=5, 2a+b-3c= 1. If m=3a+b-7c, find the maximum and minimum value of m. ..
7. It is known that the equations about x and y are1ax+2y =1+A22x+2 (a-1) y = 3. When a is a value, the equation is 1. There is only one solution. 2. There is no solution. 3. There are infinite groups of solutions.
8. If it is 0, then a+ =
9. The lowest absolute number is
10. The absolute value of rational number is equal to itself, and this number is ().
A, positive number b, non-negative number c, zero d, negative number
1 1. It is known that x and 1 are reciprocal, while | a+x | and x are reciprocal. Find the value of X2000-AX200 1.
12. For a three-digit number, the number in the hundredth digit is larger than the number in the tenth digit 1, and the number in the third digit is smaller than the number in the tenth digit by 3 times 2. If the order of the digits on the hundredth digit is reversed, the sum of the three digits obtained and the original three digits is 1 17 1, so find the three digits.
13. let a, b and c be real numbers, and | A |+A = 0, | AB | = AB, | C |-C = 0, and simplify the algebraic expression | b |-| a+b |-| c-b | |.
14. Given (m+n)*(m+n)+|m|=m, |2m-n-2|=0, find the value of mn.
15. There are four rational numbers 3, 4, -6, 10, and the result is 24. (Write four different numbers)
16. Because -(-6) = 6, the four rational numbers given in 1 are essentially the same as 3,4,6, 10. Please use addition, subtraction, multiplication, division and brackets to write the formula with the result not greater than 24.
17. Can the sum of the number obtained by arbitrarily changing the order of a three-digit number and the original number be 999? Explain why.
18. A student ran a lap on the 360-meter-long runway. It is known that his speed is 5 meters per second in the first half and 4 meters per second in the second half. How long will it take him to run half the distance?
19. Xiaoming is walking by the sea. A ship came head-on and passed him in three seconds. After a while, the boat caught up with Xiao Ming from behind and passed him for 4 seconds. Xiaoming walks at a speed of 3 meters per second. Please, captain?
20. An old man raised 17 sheep and distributed them to his three sons in proportion. The eldest son got 1/2, the second son got 1/4 and the third son got 1/9. Killing sheep is not allowed in time sharing. How to divide the sheep, and how much does each son get?
Write a group of continuous positive integers starting with 1 on the blackboard, and erase one of them, then the average of the remaining numbers is 47, which is17 (4717/31). Q: What is an erased number?
Hard to find! ! !