A, B and C take two, three and one hot water bottles respectively, and arrive at the boiling water supply point to draw hot water at the same time. There is only one hot water tap. How to arrange their order of drawing water so that they can spend the least time (including waiting time) to draw hot water? (it takes one minute to fill one bottle) what's the score?

According to the stem analysis, we should wait according to the order of C, a and B to draw water, which takes the least time. 1 × 1 × 3 + 1 × 2 × 2 + 3 × 1, = 3 + 4 + 3, = 10 (minutes). A: we should wait according to the order of C, a and B to draw water, which takes at least 10 minutes

Xiaoming and Xiaoling take the same money to buy exercise books. As a result, Xiaoming takes eight more, and Xiaoming pays Xiaoling 2.4 yuan. Xiaoming pays 7.2 yuan for the exercise books. How many exercise books does Xiaoming buy?

Xiaoming takes 8 more copies. If he gives Xiaoling 4 copies, the two exercise books are the same. We can see that the two exercise books are the same. If Xiaoming buys 4 copies from Xiaoling, 2.4 yuan is the money for 4 copies. The unit price of exercise books is 2.4/4 = 0.6 yuan
Xiaoming bought 7.2 / 0.6 = 12 copies

When a natural number is divided by 5, 6, 7, the remainder is 1, within 10000. There are many such numbers______ How many?

When divided by 5, 6, 7, the remainder is the minimum natural number of 1: 5 × 6 × 7 + 1 = 21110000 △ 210 = 47 A: there are 47 such numbers

Find the rule: 1,2,3,4,6, (), 9,12, (), 24, (), 72

Fill in 8 and 18 and 36
Because the factor of 72 is 1,2,3,4,6,8,9,12,18,24,36,72

A prime number multiplied by 4 times and 3 is prime. How much is this number multiplied by 5 times and 3?

According to the stem analysis, the prime number is 2.25 = 32, 32 + 5 = 37

For any real number AB, f (a, b) = 1 / 2 (a + B - | A-B |), if f (x) = x ^ 2, G (x) = 3x + 4, H (x) = - x + 6,
Then the maximum value of the function g (x) = f (f (x), G (x)), H (x)) is equal to

F (a, B, c) = what?
=1/2(a+b+c-|a-b-c|)
=1/3(a+b+c-|a-b-c|)
=1/2(a+b+c-|a-b+c|)
=1/3(a+b+c-|a-b+c|)

Can we simply calculate 6 divided by 2 / 3 + 4 divided by 1 / 3, 4 divided by 4 / 5

6 divided by 2 / 3 + 4 divided by 1 / 3
=9+12
=21
4 divided by 4 / 5 = 5

The square (X-Y) + (Y-X) factorization of X

x"( x - y ) + ( y - x )
= x"( x - y ) - ( x - y )
= ( x" - 1 )( x - y )
= ( x - 1 )( x + 1 )( x - y )

Application of quadratic equation of one variable,
1) The product of two adjacent even numbers is 168, find the two even numbers. 2) the sum of two right angles of a right triangle is 14cm, the area is 24cm2, find the length of two right angles

1. Let one of the numbers be x, then the other is x + 2
x（x+2）=168
x^2+2x-168=0
(x+14)(x-12)=0
X = 12 or - 14
Then these two numbers are 12,14 and - 14, - 12
2. Let one right side of a right triangle be x and the other be y
x+y=14
1/2*xy=24
x=6,y=8

What kind of water is used in the swimming pool?

First, tap water and chlorine are mixed in proportion
Second, with more swimmers, some people will urinate in the pool. In this way, the proportion of ammonia in the pool will also increase
Third, in open-air swimming, there will be acid rain caused by natural precipitation and problem water caused by pollutants falling
Fourth, developed career, healthy life and happy family