I couldn t understand a math problem, so I knelt down and begged for help

Let y be equal to the square of x, and substituting it into the original formula to get y squared minus 2 times the root number 2y plus 1 equals 0, and then the value of y can be obtained from the equation, so that y is equal to the root number 2 plus 1 or the root number 2 minus 1, so the square of x root number 2 plus 1, or equal to the root number 2 minus 1.

Can this be reversed? . . You see, if the square of x = root number 2 + 1, then the negative 2nd power of x is = root number 2-1

It is made up of x to the power of 2 times the square of x and the root number 2

Get 1 x 2 2 tidy up.

x⁴－2√2·x²＋1＝0

Let x =y then there is.

y 2 2·y 1 0 to solve the equation .

y 2 1 Yes.

x²＝y＝√2±1

It is obtained that x4 to the power - 2 times the root 2+1=0, so [x square - (root 2 + 1)]*x square - (root 2-1)] = 0

x to the power of 2 x to the square of x to the square of the root number 2

Get x4-2 2x2=-1

x4-2√2x2+2=1

x2-√2)^2=1

x2-√2=±1

x2=±1+√2

x2>=0

x2=1+√2

Let x squared = a

x2=a, then a2-2, 2a+1=0, then a-( 2+1)】=0

The rounding of the two floors is unreasonable, so that the two answers can be brought into the original style, so that one can be discarded.

If the side length of the flower bed is x, the area of the path is: 2 (x + 2) + 2x = 20, x = 4, and the area of the flower bed is: 4 4 = 16 square centimeters.

The number of blocks from top to bottom is.

a ,a +1 , a+2, …b-2, b-1, b (with n rows) from the bottom to the top of the number of blocks.

b, b-1, b-2, +a-2, a-1, a (also n lines) can be added to find that the numbers are all gone, only the letter a b, a total of n:

a+b)+(a+b)+…a+b)+(a+b) a total of n groups.

Therefore, the total is (a+b)*n

The result of this addition is that each row is used twice, so the number of tiles is divided by 2, i.e. (a+b)*n 2

When a=21, n=19, b=39, substitute the above formula.

21+39)*19 2=570 (block).

Layer 1: A+0 Layer 2: A+1 Match 3: A+2 . Layer n: A+N-1

b=a+n-1）

Therefore, the total number of tiles paved with n layers is:

a+0+a+1+a+2+a+3+a+4+..a+n-1=n*a+(0+1+2+3+4+..n-1)=n*a+n(n-1)/2

Note: 0+1+2+3+.n=n(n+1) 2 brings in 21*19+19*18 2=570 pieces.

This is mainly sequence operation, just know the formula of common sequences, I hope it will help you.

The sum of the equal difference series is n*(a+b) 2 blocks, and when a=21, b=39, n=19, there are 570 blocks in total.

Determine the number of layers b-a+1 first

Now it's a matter of the difference series, a is the first term, the layer is the number of terms, b is the last term, there's a formula for high school math. I gave it back to the teacher .........I found the formula for finding the sum of the series (a+b)*(b-a+1) 2 on the Internet

This is a series of numbers Equal difference series I don't know if you have learned the first layer a second layer a+1 the third layer a + 2 until the nth layer is a + (n-1), that is, b = a + (n - 1) So it is the sum of the equal difference series A total of na+n 2 2 And then the following set of formulas The result is 535 is counted as an integer.

Working backwards, the process is as follows.

First of all, the total is 24x3=72

The number of chestnuts in front of Xiao Liang and Xiao Ying also doubled"It shows that before the big gang score, Xiaoliang and Xiaoying each had 12, and the outline had 72-12-12=48.

Then Xiao Ying gave some of the chestnuts in front of her to Xiao Liang and Da Gang, and the number of chestnuts in Xiao Liang and Da Gang increased by 1 times" means that before Xiao Ying divided, Xiao Liang had 12 divided by 2 = 6, Da Gang had 48 divided by 2 = 24, and Xiao Ying had 72-24-6 = 42.

After Xiao Liang divided a bunch of chestnuts in front of him and gave them to the other two, the number of chestnuts in each of these two people increased by 1 time" means that before Xiao Liang scored, it was the original Da Gang had 24 divided by 2 = 12, Xiao Ying had 42 divided by 2 = 21, and Xiao Liang had 72-12-21 = 39.

Just push it back.

Xiao Liang, Xiao Ying, Da Gang.

Last 24 24 24

Da Gang Score 12 12 48

Xiao Ying points 6 42 24

Small bright score 39 21 12