What's 5 out of 27 times 63 times 3 out of 14

What's 5 out of 27 times 63 times 3 out of 14

5/27×63×3/14
=5/27×27/2
=5/2

How much is 2 times 28 out of 75

One in 51

What is 23 plus 23 times 23?

23+23*23=23*(1+23)=23*24=23*(20+4)=23*20+23*4=460+92=552

It looks very simple, but it's hard to find a math problem in junior high school
A small boat from a to B downstream a hour counter current B hours to find a piece of wood smoothly from a to B time to say why
Yes, the God creaks, not only the steps but also the reasons. I know the steps

Let the water speed be V1, the ship speed be V2, and the distance be s
Then s = a (V1 + V2)
s=B（v2-v1）
From the above two formulas, V1 = 0.5 (s / A + S / b)
Then t = s / V1 = 2Ab / (a + b)
I hope it can help you,

The image of a quadratic function is known to pass through points (0,5), (1,0), (2, - 3). Find the analytic expression of the quadratic function

Let the quadratic function be y = ax ^ 2 + BX + C
Substituting (0,5) into
5=c
Then the quadratic function is y = ax ^ 2 + BX + 5
Substituting (1,0) into
0=a+b+5
a+b=-5 1
Substituting (2, - 3) into
-3=4a+2b+5
2a+b=-4 2
Formula 2-1
a=1
b=-6
So y = x ^ 2-6x + 5

1 / 4-1 / 6 plus 2 / 3-1
In addition, I would like to ask. What is the result of meeting 1 out of 12 to 1 out of 12?
How to solve the problem in the case of fractional integer?

General division
1/4-1/6+2/3-1
=3/12-2/12+8/12-12/12
=(3-2+8-12)/12
=-3/12
=-1/4
1 / 12-1 / 12, the subtracted and the subtracted are the same, so they are equal to 0
Fractions - integers are also made up of general fractions

A + B = 4 ∫ a + 2 ∫ B-5 a + 2B =? (∫ radical)

a+b=4∫a+2∫b-5a-2b
a=4∫a(6a)-5a
∫=(5+1)/4
=1.5
b=2∫b(3b)-2a
∫=(2+1)/2
=1.5
Just OK!

When n = 1, M = 2, so the following two columns are listed
The first column n: 1,2,3,4,5,6,7,8,9
The second column m: 2,4,6,8,10,12,14,16,18
Let the sum of all the numbers in the second column be X
Q: how to find x according to the number corresponding to n given in the first column?
Please list the equations
For example, when n = 3, x = 12, what's the equation

X=n*(1+n)

Two junior high school math problems!
1. If the two sides of equation x are a and B (a > b), and the positive root of equation x-4 = 0 is C, try to judge whether the triangle with a, B and C as sides exists. If it exists, find out its area; if it does not exist, explain the reason
2. It is known that the sum of the two equations (a + C) x + 2bx - (C-A) = 0 is - 1, and the difference between the two is 1, where a, B and C are the three sides of △ ABC. (1) find the root of the equation; (2) try to judge the shape of △ ABC
3. With the continuous improvement of people's economic income and the rapid development of the automobile industry, more and more cars have entered ordinary families and become a new growth point of residents' consumption. According to the statistics of a city's transportation department, at the end of 2007, the city's car ownership was 1.8 million, and by the end of 2009, the city's car ownership had reached 2.16 million
(1) Find the average annual growth rate of car ownership in the city from the end of 2007 to the end of 2009;
(2) In order to protect the urban environment and alleviate the automobile congestion, the transportation department of the city plans to control the total number of automobiles, and requires that by the end of 2011, the total number of automobiles in the city should not exceed 2.3196 million. It is estimated that since the beginning of 2010, the number of scrapped automobiles in the city every year is 10% of that at the end of last year, Please figure out the maximum number of new cars in the city every year

(1) suppose that the average annual growth rate of car ownership in the city is X
150(1+x)2=216
The solution is X1 = 0.2 = 20%, X2 = - 2.2
A: the average annual growth rate of car ownership in the city is 20%
(2) Assuming that the number of new cars in the city is y 10000, the car ownership of the city will be 216 × 90% + y 10000 by the end of 2010 and (216 × 90% + y) × 90% + y 10000 by the end of 2011
(216×90%+y)×90%+y≤231.96
The solution is y ≤ 30
A: the number of new cars in the city can't exceed 300000 every year

Two problems in junior high school mathematics
1、 Analysis equation 2m (3x + 1) = n (3x + 1)
2、 If there are two solutions to the equation (a + b) x & sup2; - 3 (x + a) + 4-b = 0, which are 1 and 2 respectively, the values of a and B are obtained
Attach process

One
It is reduced to (6m-3n) x = n-2m
When 6m-3n = 0 and n-2m = 0, that is, n = 2m, the equation has innumerable solutions
It is impossible when 6m-3n = 0 and n-2m ≠ 0
When 6m-3n ≠ 0, x = (n-2m) / (6m-3n)
two
Substituting x = 1 into the original formula, we get (a + b) - 3 (1 + a) + 4-b = 0
Substituting x = 2 into the original formula, we get 4 (a + b) - 3 (2 + a) + 4-b = 0
① The result of simultaneous solution is a = b = 1 / 2