Ask a simple math problem in the first year of junior high school. Come on! O O thank you

x²-3x+1=0

Divide both sides by x to get

x-3+1/x=0

x+1/x=3

x+1/x)²=9

From the perfect square formula:

x²+1/x²+2=9

x²+1/x²=7

x²-3x+1=0

x-3+1 x=0 divides both sides by x (x is not 0 from the question), i.e. x+1 x=3

x²+1/x²=(x+1/x)²-2×x×1/x

Solution: 7x 2-3x+1=0

Divide by xx+1 x=3 on both sides

Original = (x+1 x) 2-2

Hope!!!

From the equation, we can get that x is not equal to 0 and 1 3, and x 2=3x-1, then the equation can be written as [(3x-1) 2+1] (3x-1) and simplified to obtain [9(3x-1)-2(3x-1)] (3x-1) then it is equal to 7

According to the known conditions, x2=3x-1 is then substituted into the required formula, and the numerator opens a perfect square, and then substituted x2=3x-1 again, and finally the answer 7 is approximated

x 2 3x 1 0x 2 1 3x1 x 2 3x both sides at the same time divided by x(1 47;x) x 3 squared on both sides (1 47;x）＾2－2＊（1＆＃47；x）＊x＋x＾2＝9（1＆＃47；x) 2 2 x 2 9 So 395 (1 47;x 2) x 2 11 Answer 9 11

Earn, because A buys fruit for 2mn, and sells fruit for (m+n) 2 2, which is a very simple inequality problem, (m+n) 2 2>2mn (m is not equal to n), so earn.

The total price of apples = m*n + n * m = 2nm

Total selling price = (m+n) 2*(m+n) = (m+n) 2 2 profit = selling price - ** price.

m+n)^2/2-2nm

m-n)^2/2

m is not equal to n=(m-n) 2 2

A makes a profit in buying and selling (m-n) 2 2

Let B be born in abcd year, from the inscription 2002-abcd=a+b+c+d, 2002=1001a+101b+11c+2d, where 0 a 2, 0 b, c, d 9, the solution is abcd=2000, or 1982, so B is 2 years old this year, or 20 years old. Since the question says that it is a young man, A is 20 years old and B is 21 years old.

The solution of the system of equations {ax+by=2,cx+2y=10 is {x=2,y=4.).Xiaohua misread the c value when doing his homework, and the solution he found was {x=3,y=, please find the value.

** The above is the problem-solving process.

1. Solution: original formula = -3 12 + 10 12 + 18 12-24 12 = (-3 + 10 + 18-24) 12 = 1 12

2. Solution: original formula = -3 2 1 4 = -3 8

3. Solution: original formula = -26 41 + 35 17 = -1066 + 595 = -4714, solution: original formula = 1 5 + 16 4 = 5 + 4 = 95, solution: original formula = -(-2) + 9 (-2) = -2-18 = -16

1.Original = -3 12+10 12+18 12-24 12=1 122Original = -3 8

3.Original = - (35x17-26x41) = -4714Original = 5 + 4 = 9

5.Original=2+9x(-2)=-16

The so-called process is to write down what you think or calculate on the straw paper, just write two steps, and finally the answer is good.

1.Original = -3 12+10 12+18 12-24 12=1 122Original = -3 8

3.Original = -1066 + 595 = -471

4.Original = 5 + 4 = 9

5.Original = 2-18 = -16

The implementation of the small time to recite the poetry book on the market, the small time to recite the poetry book on the market, in fact.

It's all oral arithmetic, you want the process? How embarrassing!

(1) In the second 2 hours, the two walked a total of 36 + 36 = 72 kilometers.

2) Two people walk together in one hour: 72 2 = 36 km.

3) The distance between the two places: 36*2+36=108 km.

The first time was 36km apart, indicating that the two had not yet met, and the second time was 36km apart, indicating that the distance between them after the encounter was 36km

Let AB distance skm, and the speed of A and B is 36km away for the first time for vkm h: s-36=2v

The second time is 36km apart: s+36=4v

The solution is s=108(km).

(1) If the number of girls is x, then the number of boys is 5 8x, and later 4 boys are transferred, then the number of boys becomes 5 8x+4, then the number of girls is 4 3 times the number of boys, then the equation 4 3*(5 8x+4)=x, and the solution of the equation can obtain x as 32

2) Suppose there are x girls in the school, according to the problem, we can list the equation 5 6x-60=540, and solve the equation to get x as 720

(1) The number of boys in the sixth grade of a school is 5 8 of the number of girls, and later 4 boys were transferred, which is 4 3 times the number of girls and boys.

If there are x girls in the country, there are:

5x/8+4)(4/3)=x;

5x/8+4=3x/4;

x/8=6;

x=48;The original 48 (1 + 5 8) = 48 + 30 = 78 people.

2) There are 540 boys in the school, which is 60 fewer than the 5 60 girls in the school, how many girls are in the school?

Girls = (540 + 60) (5 6) = 720 people.

1), let x=0, there is 1=a0

2) Let x=1There is 4 5 = a5 + a4 + a3 + a2 + a1 = 10243) so x = -1, there is (-2) 5 = -a5 + a4-a3 + a2-a1 + a0, so -a0 + a1 - a2 + a3 - a4 + a5 = 32

4) Add the expressions (2) and (3) to get a1 + a3 + a5 = 1056 2 = 528

1) Let x=0, find a0=1; (2) Let x=1, and the value is 1024; (3) Let x=-1, then a0-a1+a2-a3+a4-a5=-32, so the original value is 32; (4) From (2)+(3): 2(a1+a3+a5)=992, so a1+a3+a5=496