How does the following formula deform? From C ^ 2 + 4b-4c-12 = 0 to 4 (4-b) = (C-2) 2 How do you get the second formula?

How does the following formula deform? From C ^ 2 + 4b-4c-12 = 0 to 4 (4-b) = (C-2) 2 How do you get the second formula?

c^2+4b-4c-12=0
c²-4c=12-4b
c²-4c+4=12-4b+4
(c-2)²=16-4b
(c-2)²=4(4-b)

Look at the following formula. What's the rule?
88x8=704
888x8=7104
8888x8=71104
88888x8=711104
888888x8=7111104
8888888x8=71111104
Second question
9x9+7=88
98x9+6=888
987x9+5=8888
9876x9+4=88888
98765x9+3=888888
987654x9+2=8888888
9876543x9+1=88888888
98765432x9+0=888888888
This is a question for the fourth grade of primary school

First question
8 (n 8) X8 = 7 (n 1) 04
Second question
9 ((9-1)... (9-N), n = 0.. 7, n = 0, no such term) x9 + (7-N) = 8 (n 8)

5x + 6 = 0 to 5x = - 6.2x-1 = 0 to 2x-1 + 1 = 0 + 1
What's the second one

First

What does the formula 0.5x/30 - 0.5x / (30 * 2) = 15 / 60 mean?
It's about the linear equation of one variable!

0.5x divided by 30 minus 0.5x divided by (30 times 2) is 15 divided by 60

Observe the following formulas and their deformation process
Question 26

(1) Root (3 + 3 / 8)
Verification: 3 root (3 / 8)
=Root (9 * 3 / 8)
=Root (27 / 8)
=Root (3 + 3 / 8)
(2) N radical [n / (n ^ 2-1)] = radical [n + n / (n ^ 2-1)]
Proof: left = radical (...) =（…） =Right
It's relatively simple. Please do it yourself
(3) N radical [n / (n ^ 2 + 1)] = radical [N-N / (n ^ 2 + 1)]

Examine each of the following formulas and answer the question
63*67=4221
78*72=5616
561*569=319209
1814*1816=3294224
(1) What is the sum of the numbers in each digit of the two factors? What are the characteristics of the numbers in the rest of you?
(2) According to the calculation of the four formulas, it is conjectured that the operation law of multiplication of two numbers conforming to the above characteristics
(3) Give another two calculation problems that are in line with the above characteristics, and use your conjecture to calculate

1. The sum of single digits is 10, and the rest are the same
2. This algorithm is called combining ten with the same head and tail, that is to say, when ten digits are the same, if the sum of each digit is equal to ten, the number obtained by multiplying one digit by one digit can be filled in the end, and then the number of the first digit multiplied by one digit larger than the second digit can be written in the first place
For example: for 23 × 27, you fill in the end with 3 × 7 = 21, and then fill in the first place with 2 × (2 + 1) = 6, which is equal to 621
3. Many examples: 123 × 127 = 15621, 12 × 18 = 216

Observe the following two groups of formulas,
Observe the following two groups of formulas,
Group 1:
1.0+1=1²
2.1+3=2²
3.3+6=3²
4.6+10=4²
5.______________ ,
6.______________ ,
.
The second group
1.0=1/2*1*0
2.1=1/2*2*1
3.3=1/2*3*2
4.6=1/2*4*3
.
(1) According to the law reflected by the first group of equations (1) - (4) and itself, complete equation (5 (6) (fill in the horizontal line directly)
(2) Combined with the second group's analysis of the first number of the first group, the nth formula of the first group is expressed

5._ 10+15=25_____________ ,
6._ 15+21=36____________ ,
n(n-1)/2+(n+1)n/2=n^2

What is 2 / 3 of 1.2 / 1? What is 2 / 5 of 5 / 6 of 2.24?
How much less is 1 / 5 of 3.15 than 4 / 5? How much less is 1 / 12 of 4.26 than 7 / 11 of 121?

What is 2 / 3 of 1.2?
1/2×2/3=1/3
What's 2.5 out of 24?
24×5/6×2/5=8
How much less is 1 / 5 of 3.15 than 4 / 5?
15×（4/5-1/5）=9
How much less is 1 / 12 of 4.26 than 7 / 11 of 121?
121×7/11-26×1/12=77-13/6

There are 18 technicians, 12 technicians and 6 engineers in a certain unit. We need to take a sample with a capacity of N from these people. If we adopt the method of systematic sampling and stratified sampling, we do not need to eliminate the individual. If we increase the capacity by one, we need to remove one individual from the population when we adopt the method of systematic sampling, then the sample size is ()
A. 4b. 5C. 6D

There are 18 technicians, 12 technicians and 6 engineers in the unit, with a total of 36 people. We need to take a sample with a capacity of N from these people. If we use the method of systematic sampling and stratified sampling, we do not need to eliminate individuals. If 18, 12, 6 and 36 can be divided by N, we can remove two answers a and B

It is pointed out that the equation x = ay ^ 2 (a > 0) has parabolic vertex coordinates, focal coordinates and quasilinear equations
Find out the calculation process

Fixed point coordinate is (0,0), to do this problem, first draw the parabola image. Is the parabola opening to the right
The so-called vertex is the point with the minimum value of X, which is (0,0)
Forget the concept of focus and quasilinear equation